Bathroom Water Heater Issues

[Sheryl]

I have a Stiebel water heater in my bathroom, the kind the water runs through (as opposed to they type that holds a certain amount of water) but not attached to a shower device, rather attached to separate hot and cold water faucets. installed it so I could take both hot baths and showers.

When showering, I can get a good flow of all hot water, or a good flow of cold water, but I can't seem to get both to mix to result in a comfortable temperature. If I have only the hot on it is too hot, if I add even a small amount of cold then it becomes all cold.

Running it as a bath, I can mix the two OK but the flow from the hot is very slow.

I seem to have adequate water pressure otherwise.

I am assuming that somehow I do not have enough water pressure for the hot water heater resulting in a low flow of hot at low pressure which when the hoigher pressure cold is on effectively blocks it. Alrtho as mentioned the pressure otherwise seems fine, it is only 1 story up and the cold water comes out full force.

Does this make sense? Am I overlooking anything? And how to solve, the pipes are not accessible unless I want to tear apart the wall tiles. I have looked to see if there was a filter mechanism an where on the water heater that might be clogged but doesn't seem to be one.

[mosass69]

The problem is simple. There are two types of water heaters.

1. One is for showers it will warm the water to a comfortable tempature. The only way to get cold water is to shut it off and just run the water through it without it on. Most Thai style apartments have only one water line running in.

2. (WHich i think you Have) is for HOT water only so you will need two water lines running in. You will need a cold as well as this line which is hot. So there is really no way to get warm water as you would with style one unless you have the cold water to mix.

It has nothing to do with pressure. What model of stiebel do you have so I can confirm.

[Crossy]

What model of stiebel do you have so I can confirm.

Yes! and a photo of the installation would be handy.

We had a similar problem, turned out that the shower head was bunged up and turning on the cold shoved the water backwards through the heater, cleaning out the crud in the shower head was an easy fix

[T_Dog]

I have a Stiebel water heater in my bathroom, the kind the water runs through (as opposed to they type that holds a certain amount of water) but not attached to a shower device, rather attached to separate hot and cold water faucets. installed it so I could take both hot baths and showers.

When showering, I can get a good flow of all hot water, or a good flow of cold water, but I can't seem to get both to mix to result in a comfortable temperature. If I have only the hot on it is too hot, if I add even a small amount of cold then it becomes all cold.

Running it as a bath, I can mix the two OK but the flow from the hot is very slow.

I seem to have adequate water pressure otherwise.

I am assuming that somehow I do not have enough water pressure for the hot water heater resulting in a low flow of hot at low pressure which when the hoigher pressure cold is on effectively blocks it. Alrtho as mentioned the pressure otherwise seems fine, it is only 1 story up and the cold water comes out full force.

Does this make sense? Am I overlooking anything? And how to solve, the pipes are not accessible unless I want to tear apart the wall tiles. I have looked to see if there was a filter mechanism an where on the water heater that might be clogged but doesn't seem to be one.

Gee, I thought we were the only ones having problems with this! Our new rental house has the same type of installation with a 12KW Siemans unit. Inside, there were three separate elements with a barrier strip to connect them up in various configurations. I simply disconnected one jumper to get the power rating reduced. Don't do this yourself unless you are experienced with electrical work and can be confident the area is powered down. Call an electrician.... they should be able to do it for you if the heaters are configurable. Also, look for a flow limiter somewhere in the hot water line or in the source water. It could be set to low.

Edited October 2, 2009 by T_Dog

[Thongkorn]

Sounds like the Diverta valve. If it has a rubber diaphram its probably us . It works under pressure , over the years it weakens and splits , giving you to hot or none , Hope that helps you. I tip don't get a new diaphram and fit it get a complete new unit because when you repair them they usually leak because the seal that has built up over time has been broken,

[Sheryl]

I'm in a custom built house, not an apartment. The heater is a Stiebel Eltron DHA 4/12T, type #2 as described by Mosass69 i.e. it is for hot water only. There are separate hot and cold lines altho they bifurcate off the same initial line, i.e. one side, controlled by the cold water knob on the faucet, goes straight into the shower or tub while the other, controlled by the hot water knob on the faucet, goes through the heater and comes out hot.

So I do have both hot and cold. My problem is getting them to mix as having the cold on seems to shut off the hot or at least slow it down to an imperceptible flow. It is not a new problem, has been the case ever since isntalled when house first built. So whatever it is due to, it's not something wearing down.

Local electricians utterly unable to do anything with it (they fall far short of much simpler tasks than this, to put it mildly). I would at minimum need to be able to tell them exactly what needed to be done and virtually draw them a diagram. I'm out in the boondocks and quality of "electricians" is abyssmal beyond words.

I can't identify anything inside that looks to be a flow meter or other control, but I have not looked inside the large cylinder that occupies most of it, is that where it would be? I'd post picture but am not at home now.

Thanks all....

Possibly a flo9w meter and other controls are located inside the cylinder? I have not ventured to open that as I don't know what I am doing.

[longball53098]

I'm in a custom built house, not an apartment. The heater is a Stiebel Eltron DHA 4/12T, type #2 as described by Mosass69 i.e. it is for hot water only. There are separate hot and cold lines altho they bifurcate off the same initial line, i.e. one side, controlled by the cold water knob on the faucet, goes straight into the shower or tub while the other, controlled by the hot water knob on the faucet, goes through the heater and comes out hot.

So I do have both hot and cold. My problem is getting them to mix as having the cold on seems to shut off the hot or at least slow it down to an imperceptible flow. It is not a new problem, has been the case ever since isntalled when house first built. So whatever it is due to, it's not something wearing down.

Local electricians utterly unable to do anything with it (they fall far short of much simpler tasks than this, to put it mildly). I would at minimum need to be able to tell them exactly what needed to be done and virtually draw them a diagram. I'm out in the boondocks and quality of "electricians" is abyssmal beyond words.

I can't identify anything inside that looks to be a flow meter or other control, but I have not looked inside the large cylinder that occupies most of it, is that where it would be? I'd post picture but am not at home now.

Thanks all....

Possibly a flo9w meter and other controls are located inside the cylinder? I have not ventured to open that as I don't know what I am doing.

Sheryl,

Sorry to hear of you're dilemma with the water heater. I will give you my 10 baht worth of thinking on this problem and what I think you can do about it.

First let me say looking at the Stiebel web site for Asia I do not see a model 4/12T listed, only a 4/6 or a 4/8 in the DHA series. But this is not why I want to comment as the "multipoint" units all operate about the same in this series of heaters.

I will also add that I recently installed a new Stiebel heater only mine is higher powered a model DHF 12C1. This model has two heat settings. 12kw or 6kw. I only use the 6kw setting as this is hot enough.

So now here is my theory about what you're water heating/mixing problems are and possibly what to do to make it better.

The heater you have most likely is working correctly. It has a heating element somewhere in the 4 to 12 thousand watt range depending on the model. When you open the mixer valve at the shower or bath the water flow will cause the flow switch in the heater to sense the flow of water and turn on the heating elements. Water will get heated as long as the flow of water remains high enough to keep the flow switch activated. So now you have very hot water coming out of the mixer valve so you decide to add some "cold" water to the mix to get a nice comfy shower. When you move the controls of the mixer the water flow from the heater is reduced as the mixer valve is moved over to the cold position and more cold water is allowed to flow. If you reduce the hot water flow enough it will cause the flow switch to shut off the heater as there now is not enough of a flow through the heater for it to heat correctly without burning out an element.

Now this is where the problem begins. Most likely the "cold" water is not really cold. Here in LOS the normal water temperature coming from the supply pipes is most likely around 23C or higher depending on where you are and the season of the year. Add to this if the water supply is coming from a sun heated tank or any other thing that will raise the standing water temps. So the "cold" water that you try to mix into the hot water is really not "cold" enough to make a difference when added to that hot water from the heater. The water from the heater is just too hot and cannot be cooled enough using the "cold" water side of the valve. There is nothing really wrong with you're heater, the water pressure or the valves or other plumbing. If you could regulate the temperature of the water being heated in the heater then the problem would be solved. But in the case of the heater you have its all or nothing. As the heater works on flow and not an electronic control to regulate the heating elements.

The solution to this problem is make the water supply colder if possible. Or buy a heater that has an electronic control unit and you can set the output temperature of the hot water to whatever that unit will allow. Stiebel makes a DHE series that does this and they sell remote controls so the unit can be adjusted from the shower cubicle.

I can speak about this issue as I have the same problem here in my new house. My DHF heater set on the 6kw setting is too hot and I have the same issues when showering during the hot day time. We cannot add enough "cold" water to make a cool shower before the heater shuts down. The problem is much less noticeable now in the cool, rainy weather with the water temps down in the low 20's but even at the slowest water flow from the heater my wife still complains its too hot. I am seriously considering the electronic model from Steibel

So I hope I didn't make this too confusing and I hope it makes sense to you. But this is my theory and I'm sticking to it.

[offset]

I'm in a custom built house, not an apartment. The heater is a Stiebel Eltron DHA 4/12T, type #2 as described by Mosass69 i.e. it is for hot water only. There are separate hot and cold lines altho they bifurcate off the same initial line, i.e. one side, controlled by the cold water knob on the faucet, goes straight into the shower or tub while the other, controlled by the hot water knob on the faucet, goes through the heater and comes out hot.

So I do have both hot and cold. My problem is getting them to mix as having the cold on seems to shut off the hot or at least slow it down to an imperceptible flow. It is not a new problem, has been the case ever since isntalled when house first built. So whatever it is due to, it's not something wearing down.

Local electricians utterly unable to do anything with it (they fall far short of much simpler tasks than this, to put it mildly). I would at minimum need to be able to tell them exactly what needed to be done and virtually draw them a diagram. I'm out in the boondocks and quality of "electricians" is abyssmal beyond words.

I can't identify anything inside that looks to be a flow meter or other control, but I have not looked inside the large cylinder that occupies most of it, is that where it would be? I'd post picture but am not at home now.

Thanks all....

Possibly a flo9w meter and other controls are located inside the cylinder? I have not ventured to open that as I don't know what I am doing.

Sheryl,

Sorry to hear of you're dilemma with the water heater. I will give you my 10 baht worth of thinking on this problem and what I think you can do about it.

First let me say looking at the Stiebel web site for Asia I do not see a model 4/12T listed, only a 4/6 or a 4/8 in the DHA series. But this is not why I want to comment as the "multipoint" units all operate about the same in this series of heaters.

I will also add that I recently installed a new Stiebel heater only mine is higher powered a model DHF 12C1. This model has two heat settings. 12kw or 6kw. I only use the 6kw setting as this is hot enough.

So now here is my theory about what you're water heating/mixing problems are and possibly what to do to make it better.

The heater you have most likely is working correctly. It has a heating element somewhere in the 4 to 12 thousand watt range depending on the model. When you open the mixer valve at the shower or bath the water flow will cause the flow switch in the heater to sense the flow of water and turn on the heating elements. Water will get heated as long as the flow of water remains high enough to keep the flow switch activated. So now you have very hot water coming out of the mixer valve so you decide to add some "cold" water to the mix to get a nice comfy shower. When you move the controls of the mixer the water flow from the heater is reduced as the mixer valve is moved over to the cold position and more cold water is allowed to flow. If you reduce the hot water flow enough it will cause the flow switch to shut off the heater as there now is not enough of a flow through the heater for it to heat correctly without burning out an element.

Now this is where the problem begins. Most likely the "cold" water is not really cold. Here in LOS the normal water temperature coming from the supply pipes is most likely around 23C or higher depending on where you are and the season of the year. Add to this if the water supply is coming from a sun heated tank or any other thing that will raise the standing water temps. So the "cold" water that you try to mix into the hot water is really not "cold" enough to make a difference when added to that hot water from the heater. The water from the heater is just too hot and cannot be cooled enough using the "cold" water side of the valve. There is nothing really wrong with you're heater, the water pressure or the valves or other plumbing. If you could regulate the temperature of the water being heated in the heater then the problem would be solved. But in the case of the heater you have its all or nothing. As the heater works on flow and not an electronic control to regulate the heating elements.

The solution to this problem is make the water supply colder if possible. Or buy a heater that has an electronic control unit and you can set the output temperature of the hot water to whatever that unit will allow. Stiebel makes a DHE series that does this and they sell remote controls so the unit can be adjusted from the shower cubicle.

I can speak about this issue as I have the same problem here in my new house. My DHF heater set on the 6kw setting is too hot and I have the same issues when showering during the hot day time. We cannot add enough "cold" water to make a cool shower before the heater shuts down. The problem is much less noticeable now in the cool, rainy weather with the water temps down in the low 20's but even at the slowest water flow from the heater my wife still complains its too hot. I am seriously considering the electronic model from Steibel

So I hope I didn't make this too confusing and I hope it makes sense to you. But this is my theory and I'm sticking to it.

Maybe you could test this theory by running the hot water in the bath when you have a shower which should keep the flow switch open you would only need to run the water in the bath just enough to get hot water I do not have one of these heaters so I am only guessing

[longball53098]

This idea is not too bad as i have done something similar. I feed 2 sinks and 3 showers from my one heater so I have tried running hot water from say shower 1 and then used shower 2 and adjusted the mixer on shower 2 to get a halfway decent temp. Keeping shower 1 open on hot seems to help the problem but a heck of a waste of water.

I just think these multipoint units are really not meant for areas like this with cold water that's not really cold. I think a better solution would be to use a single point heater that is a higher wattage say 4kw or 6kw and connect it just like a multipoint unit to feed a mixer valve. The single point units have a thermostatic control to keep the unit at a lower power and not over heating the water. Should work ok in theory. This method would require a trial and error method to find a good setting for the temp control as the unit would be located away from the user under a sink or somewhere.

[elkangorito]

There are separate hot and cold lines altho they bifurcate off the same initial line, i.e. one side, controlled by the cold water knob on the faucet, goes straight into the shower or tub while the other, controlled by the hot water knob on the faucet, goes through the heater and comes out hot.

The heater you have most likely is working correctly. It has a heating element somewhere in the 4 to 12 thousand watt range depending on the model. When you open the mixer valve at the shower or bath the water flow will cause the flow switch in the heater to sense the flow of water and turn on the heating elements.

She does not have a "mixer valve". She has two separate taps.

The problem can only be one of two things;

1] the total water supply flow rate is not sufficient.

2] pipe sizes (flow rates) for the cold water throughput & the hot water throughput are such that when the cold water tap is opened, the water pressure restricts the flow of the hot water outlet. Think of two resistors in parallel, one resistor being very large & the other being very small.

[Sheryl]

Thanks for these ideas.

For sure, when the cold tap is opened the water pressure has the effect of either stopping the hot altogether or slowing it to imperceptible. I should add that even when only the hot is on, the flow volume is low -- lower than one would like and definitely much lower than the cold. Since there is only 1 pipe initially coming into the house I assume it starts out at the same pressure but something in the process of it passing through the hot water heater slows it way down. But why? I would expect some slowing perhaps but not like this.

Surely they would not have made it such that there is a major loss of prressure as a result of passing through the heating element? Perhaps the gauge of the pipes running up to and/or from the hot water heater are for some reason smaller than those of the water as it first comes in? (no way to tell without tearing apart wall tiles)? The contractor who installed the plumbing was completely clueless as regards western bathing habits, hot water heaters and the like. (I will spare all the gory details save to mention that he hooked up the drain from the tub in such a way that the water spouts back up from the floor drain in the bathroom below. When I complained he expressed shock that I was actually filling up the tub with water and said it was only to be expected if I did an odd and unexpected thing!)

I think the total water supply flow rate is OK. Certainly seems to have a good pressure otherwise, plus in another bedroom where I have only a shower and one of those shower-connected water heaters there is no problem.

I had considered the idea of getting a new one with controls so that I could just run the hot. But as the heater obviously still works was hoping to avoid this...and the necessity for once again having a contractor doing things to my plumbing :D

So before I give in and do this...any other suggestions? Should I bother taking apart the cylinder thing to see if I can detect any sort of control switch in there? Altho seems to me that if they had made it with any type of controls, they'd be located where they could be accessed without dismantling anything....

[ZZZ]

Your main problem is most likely what longball says. To confirm this turn on the hot water in you wash basin while you have a shower and see if that works. By doing that there will be a flow trough the heater and it will not switch off.

The flow rate problem could be due to a too small rubber bushing. I guess that the heater is connected to the water pipes with two flexible hoses, one from the water supply and one going out to the faucet and shower. Remove these and check that the rubber bushings are big enough and that there is no blockage. In my installation they had used a bushing that was very small and restricted the water flow, after changing this everything worked fine.

[fremmel]

Since you're having low flow problems coming out of the heater another thing you can check is to see if the heater has a sediment filter that needs cleaning. My heater came with a sediment screen incorporated into the valve on the input line. If it's dirty it may be cutting the flow rate enough to not let the heater kick in when the pressure is reduced by opening the cold tap.

[longball53098]

Another thought on the lower flow from the heater? On my unit there is a small diverter valve that is part of the unit that is used when the unit is installed using pipes coming out of the wall from the back versus up from the bottom. Sounds confusing I know but if this valve is not in the correct position it will impact the input to the heater and hence the output. Maybe the unit you have is similar and has this valve. Here is a drawing from the manual.

The suggestion that something is slowing the water down in the heater is true and I think that Stiebel and others build in flow control so that the heater has time to heat the water properly. If unrestricted water flowed across the heating element if the water is too cold as in the northern climates then the heater could not effectively heat the water. If there is as said some sort of bushing in the input line maybe removing it will increase flow but I would be cautious playing around with this as it is a designed in part of the unit.

I would not attempt to open the "cylinder" or tank. Removing the covers for normal service items yes but be sure the power is switched off.

You could check water flow to the unit by removing the input connection and turning on the water and see if the flow at the input hose matches other cold water flow in other parts of the house. Maybe something is restricting the water coming into the unit.

I do notice a different water flow from my heater at any hot tap. Dramatically slower than the cold. I have a Grundfos pump and I know my pressure is good and strong. I have a second heater on my kitchen sink made by Fujika and it is the same lower flow rate when only hot is used. This kind of backs up my theory that the manufacturers build in flow restriction to allow the water to heat properly.

If these types of heaters is new to you as opposed to the storage tank type of hot water supply say from the USA then you have some adjusting to do. In the USA we get full flow and pressure from hot or cold all the time.

I go back to my thought of installing a heater that has a thermostat that controls the heat of the water. The multipoint units that use this method are expensive though.

You mention bathroom 2 has the normal wall mounted unit to the shower. The water temp on this type of heater is controlled by the dial from off to full heat. The water input to this unit is restricted also but you don't notice it. This heater will cut off also if the flow or pressure is reduced below the settings of the switches in the unit.

So bottom line is I still think there is no real problem except the water in your house is too warm to begin with and you cannot make it just a little warmer using the high powered central heater. The unit in the 2nd bath when used most likely is set to a lower heat setting to make the shower comfortable. Plus this unit is probably a 4kw or lower unit as opposed to the 6kw or higher for the other one

[Sheryl]

Wow, really appreciate the time you have all taken to try to help me with this!

The heater is for the tub/shower only and not connected to the sink or other point so I can't do the test suggested of running hot water into the sink.

I have checked in vain many times for a sediment filter, doesn't seem to be one. In fact there isn't much of anything visible except the large cylinder.

longball, if I have anything like what your diagram shows then it is behind the wall tiles where I cantr get at it (without removing wall tiles, that is).

LB & zzz, what is "bushing" and where would I find it if I have it? (I fear also behind the wall tiles?)

I am used to these types of heaters but what I have is seriously low flow, so low that even running only the hot I can't take a hot bath because by the time it is anywhere near full the water has started to cool off. I compensate by filling it first with cold water and then the hot but still not very satisfactory. And can't take a hot shower as it is either be scalded (if no cold turned on) ir else having the cold on turns off the hot.

It does sound like I either have to take a chisel to the wall tiles or buy a new heater. Not terribly happy with either option but will see. Removal of wall tiles only something I would consider if I can find replacement tiles of same color as otherwise I'd have to redo the whole &^$( bathroom. On the other hand if the problem is in the hook up and I buy a new heater I may still have a really lousy flow rate....so I guess I should try to find tiles and plan on hacking through to see inside first.

In case I do (find wall tiles of same color and hack my way through to the hook-up to the pipes), on the diagram you show LB which is the valve, is it #6? And what does bushing look like/where would it be?

Thanks again

[ZZZ]

Sorry, thought it was hooked up to the sink as well. Anyway, if possible let the hot water run in the tub at the same time as you are using the shower and see if it works. If it works then to problem is what longball suggested and there is not really any other solution than having the hot water running in the tub while using the shower. In the colder season it may not be a problem as longball suggests.

Some heaters are connected to the water supply via flexible hoses but it sound like yours is connected directly in to the wall? If that is the case you have to remove the unit from the wall to check the bushings.

The bushings you need to check are the grey round things in longballs drawing, they are made of rubber and are usually black or red and are there to prevent leaks in the fitting. Check so the orifice in the bushing is large enough, if it's smaller that the fitting it will restrict the flow.

[longball53098]

I would not be ripping in to any walls at this point. My drawing is an example of what my unit looks like with the cover off. Can you post a photo of the unit you have?

The valve in my unit is under the plastic cover not behind any walls or tiles.

I would say we need to clearly ID the unit you have so maybe we can get some technical info from Stiebel's web site

You refer to this large cylinder that can be seen? Where is the heater mounted? On a wall or under a sink on the wall or? What are its physical dimensions? A picture is worth a million words.

[Sheryl]

ZZZ I don't understand, how can I possibly run hot water into the tub while taking a shower? Either the faucet is set to tub or set to shower. Has one of those things you pull upward to route the water to shower, when down it goes to tub. Can't go to both.

There is nothing on the Steibel website, my model is not listed, already checked at length. And sent Stiebel an email they have not answered. I bought this more than 10 years ago so probably a discontinued model.

With the plastic cover on, all that I have is the unit and then short connecting tubes (the type used to connect sinks or toilets to water source) which attach to a point on the wall. Everything else is behind the tiles. When the plastic cover is removed, there is a large plastic cylinder inside within which there is I know not what and other than that there isn't too much else..for sure not a filter or any kind of control.

Picture as soon as I resolve some technical issues with my camera and card reader.

[longball53098]

ZZZ I don't understand, how can I possibly run hot water into the tub while taking a shower? Either the faucet is set to tub or set to shower. Has one of those things you pull upward to route the water to shower, when down it goes to tub. Can't go to both.

There is nothing on the Steibel website, my model is not listed, already checked at length. And sent Stiebel an email they have not answered. I bought this more than 10 years ago so probably a discontinued model.

With the plastic cover on, all that I have is the unit and then short connecting tubes (the type used to connect sinks or toilets to water source) which attach to a point on the wall. Everything else is behind the tiles. When the plastic cover is removed, there is a large plastic cylinder inside within which there is I know not what and other than that there isn't too much else..for sure not a filter or any kind of control.

Picture as soon as I resolve some technical issues with my camera and card reader.

Ok ! Now I am seeing more and I guess I got the mistaken impression this was all new stuff we were talking about. So correct me if wrong but the heater and piping and all is 10 years old? Do you know if the hot water pipes are steel? Is this flow and heating problem just started in the last month or two or has it been getting like this over the years? Could we be dealing with corroded pipes? I have seen steel pipes here that started as half inch inside diameter and slowly corroded to less than quarter inch and such low flow that it not usable.

Waiting to see the photos now.

[ZZZ]

Ok Sheryl, I thought that may be the case, that's why I said "if possible".

I think all you can do is to check the bushings in the short connecting tubes connecting the water supply to and from the heater to the wall. Remove the tubes completely, from the unit and the wall, and check so the bushings are big enough and that there is no other blockage.

Also check the water pressure coming out of the wall when you have the water heater disconnected from the supply, if this is good there will be no need to dig into the wall.

Don't think is a corrosion problem as you have had this problem since installation.

[longball53098]

ZZZ are you saying that they lived with this for 10 years? I don't think so. based on the posts here this has become an unacceptable issue just now or recently. Based on what is said that if this were an issue 10 years ago the problem would have been fixed by now.

[ZZZ]

I'm in a custom built house, not an apartment. The heater is a Stiebel Eltron DHA 4/12T, type #2 as described by Mosass69 i.e. it is for hot water only. There are separate hot and cold lines altho they bifurcate off the same initial line, i.e. one side, controlled by the cold water knob on the faucet, goes straight into the shower or tub while the other, controlled by the hot water knob on the faucet, goes through the heater and comes out hot.

So I do have both hot and cold. My problem is getting them to mix as having the cold on seems to shut off the hot or at least slow it down to an imperceptible flow. It is not a new problem, has been the case ever since isntalled when house first built. So whatever it is due to, it's not something wearing down.

Local electricians utterly unable to do anything with it (they fall far short of much simpler tasks than this, to put it mildly). I would at minimum need to be able to tell them exactly what needed to be done and virtually draw them a diagram. I'm out in the boondocks and quality of "electricians" is abyssmal beyond words.

I can't identify anything inside that looks to be a flow meter or other control, but I have not looked inside the large cylinder that occupies most of it, is that where it would be? I'd post picture but am not at home now.

Thanks all....

Possibly a flo9w meter and other controls are located inside the cylinder? I have not ventured to open that as I don't know what I am doing.

I was just referring to what Sheryl said. Agree, it should have been fixed years ago!!

[longball53098]

I guess I didn't read that the first time through. My old eyes are failing me. Appears to have been an issue.

[Sheryl]

Should have been fixed years ago, indeed, but never had any luck. Just happened to see posts about water heaters and the like in this forum which gave me renewed hope of finding the answer...I won't bore you with details of my unsuccessful attemopts to get a local "repairman" to deal with it. &^$%

But yes, it has always been thus so not due to corroded pipes.

ZZZ, will do as you suggest but first please tell me: what are "bushings" ? I haven't a clue..

Here is pix with the cover of the unit taken off:

I assume the bushings would be something inside the 2 metal tubes that come down from this and connect to the wall?

[elkangorito]

Sheryl, I'm surprised that you have survived so far!

In any other country, a plumber would look at flow rate. This will also equate to available water pressure.

Until the water pressure is known, all else is guess work. When someone asks you, "Is your water pressure good?" & you reply, "Yes", what does this mean? To a plumber, it means nothing!!! To me, it means nothing.

I really think you need to look at your water supply pressure.

[ZZZ]

Correct Sheryl the bushings, or rubber seals, will be at both ends of the hoses going down from the water heater. In longballs drawing, post#14, they look like gray rings, they are made of rubber and are usually red or black. These comes with different size orifice, if this is to small it will restrict the flow.

Looking at your picture and at longballs drawing there is one thing you should check first. On the drawing there is a small valve on top of the fitting (no 6). There is also a magnified view of this valve. On your picture it looks like you have something like that on your heater. Make sure that this valve is in the fully open position, you probably need to get in there with a screwdriver or something, hard to see on the picture.

Obviously the power must be disconnected at all times when the cover is off the heater.

[fremmel]

From your picture it looks like there are multiple heating elements for your heater. I don't see one in the picture but it's possible that there is an internal switch to turn off one or more elements. I've seen heaters like this with a summer/winter switch to do that. If not, and if you can find a knowledgeable person to do it, you can just disconnect one or more of the elements so that the water doesn't get heated as hot. I had to do this with a Siemens water heater in an apartment I lived in that was having problems similar to yours.

[elkangorito]

From http://www.stiebeleltronasia.com/servicesdetail.php?id=5

Basic maintenance of Multi Point Units.

Easy way to check and do maintenance instantaneous water heater

1. Unit must be installed vertically only.

2. When rotating unit for to set water connector at bottom, water inlet pipe should be connected to the right side of unit.

3. Release some water before connect to inlet to keep inlet pipe filter clean.

4. After installation, open water valves to put water in until pipe network and unit are free of air before switch on electricity.

5. Breaker must be at proper size eg. For unit of 6000,8000, or 12000 watts, breaker must be at size of 30,40,or 60 amp consequently.

6. Switch on electricity, open cover and check electricity at terminal block. If no electricity, please check breaker on or off.

7. If breaker is on but unit still not work, Reset unit may be needed. To do reset, breaker must be off, then open cover and press reset button at Thermostat (please check with manual to address Thermostat button).

8. Keep cleaning inlet filter so often by disconnect cold water valve then remove and clean filter.

9. Clean shower head filter to prevent low water volume.

10. Low or not constant water pressure can cause problem of hot and cold water out simultaneously, or unit does not work. This case water pressure should be adjusted.

11. Maximum water valve opening can cause low water temperature due to quickly water flow in and out from unit.

12. For safety, please check and adjust water temperature before using.

13. If water cannot mix, please clean or remove shower head filter.

To solve your problem, you must eliminate the known possibles, as above.

After these possibilities have been eliminated, further diagnosis is required.

Edited October 12, 2009 by elkangorito

[Sheryl]

From your picture it looks like there are multiple heating elements for your heater. I don't see one in the picture but it's possible that there is an internal switch to turn off one or more elements. I've seen heaters like this with a summer/winter switch to do that. If not, and if you can find a knowledgeable person to do it, you can just disconnect one or more of the elements so that the water doesn't get heated as hot. I had to do this with a Siemens water heater in an apartment I lived in that was having problems similar to yours.

I don't see anything that looks remotely like a switch. Disconnecting one of the elements sounds more promising if (and it is a big if) I can find someone capable of doing it. Sorry to sound dumb but which in this diagram are the heating elements? Is it the upper right corner stuff?

zzz: which part of my unit do you think may be a valve, to me none of it looks what is in the drawing?

Ah so "bushings" are what in the US we call washers? The black rubber things that help to provide a secure seal? I'll check them.

Elkan: the unit is not a shower unit so no shower head. And it has no inlet filter, at least none I have ever been able to discover. I think maybe these instructions relate to a different type of unit. Re water pressure, the unit works in terms of producing very hot water (so there must be enough pressure to trigger it), other heater in other BR (of the shower head type) works fine and overall pressure seems fine, also I replaced the water pump once already and no change. Granted no one has measured the exact flow rate but seems to me from my limited understanding that if the problem was insufficient water pressure the unit would not turn on and heat?

One of the things that puzzles me is that this problem occurs even if the cold is on very slightly. I can understand, given that the cold does obviously run at higher pressure and volume than the hot, that when both are on the higher pressure of the cold might prevent the hot from flowing, or slow its flow to a point which causes it to shut off. I try to compensate for this by turning on the cold only to a small trickle. But still it shuts the hot off. Is it possible that in installation (which as mentioned was done by an idiot) somehow the it was set up so that when one tap is on the other is off? I don't really know how that might happen, perhaps some valve within the faucet set up or connected to it that only allows one opening? Just wild guess.

[longball53098]

Maybe I can make a suggestion on a way to check flow and pressure? Consult someone if this confuses you or it's just not clear. What I want you to do requires removing the hose connections to the heater in order to bypass the water into and out of the heater so be sure it has no power and be sure you have rags and stuff handy for the water leaks. Do not attempt this if you are the least bit unsure. Don't hesitate to say there is no way you would do this.

Please if any of the plumbing/electrical gurus here see a flaw in my idea lets hear it before we proceed.

First TURN OFF the power to the heater!

Second TURN OFF the supply of cold water to the heater.

Third, and this is the part that is difficult to explain because I cannot see the two hoses that connect the heater in and out water.

Fourth,Unscrew the right hand hose from the heater tubing connector and leave the other end attached to the wall connection.

Fifth,Unscrew the left hand hose from the wall connection but do not unscrew it from the heater.

Sixth, Now connect the right hand hose that comes from the wall cold water supply to the left hand wall connection feeding the tub. Make it tight.

Do not turn on any power to the heater!! NO POWER!

Seventh, TURN ON the water supply again and check for leaks and then check the flow/pressure at the tub using the hot side valve. Is the flow better or worse than before? Compare the flow to the cold side. Is the flow about the same? Or is the flow on the hot side still low?

What I am trying to do here is take the heater out of the water flow circuit. If you did this correctly the flow should be good at the hot water tap on the tub. If the flow is no good or still low then I would say you have some restriction in the piping to or from the heater and its not the heater. If the flow is pretty strong and not weak like before then I would say the restriction is the heater.

Eighth, After completing this little test reverse the steps to reconnect the heater the way it was. When finished TURN ON the water supply first and run some water through the heater to be sure you have all connections correct and then turn the power on again and make sure it works.

I hope this is clear and of course if one of the plumbing experts sees some serious flaw in my suggestion please speak up. I'm just trying to help and it seems like a good plan.