Bathroom Water Heater Issues

[elkangorito]

Sheryl, your piping arrangement should be as per the attached drawing (piping arrangement.pdf).

piping_arrangement.pdf

Also, these type of water diverting fixtures (pull the knob to divert water from bath to shower), leak water...they do not provide a complete seal from one output to the other. Consequently, you will lose a bit of pressure to the heater. Does water leak out of the bath tap when you have pulled the knob (set to 'shower')?

Since all other possibilities seem to have been explored & virtually exhausted, there seems to be two remaining possibilities:

1] Calcification of the pipes within the heater. Since you have said that you have had this problem from 'day one', I'm reluctant to suggest that this is the problem, although the 'town water' in Thailand is very "hard" (high calcium & iron content).

2] Not enough water pressure (flow) to the heater. I notice that the specs (as per your photo) say:

i] Max flow - 5 litres per minute. I would therefore imagine a minimum flow of no less than 2.5 litres per minute (based on other heaters on the Stiebel website). You need to test this. Get a bucket (or something) & make sure that the water output from the heater falls between these two levels (minimum 2.5 litres per minute & maximum 5 litres per minute). This should be measured from the output from the heater. If this test fails, then I suggest you need a higher water pressure (more flow) to the heater.

I have looked at the attached pictures & have concluded that your heater is not electronically controlled (easy to see). It appears to have a standard 'pressure operated' switch. The only thing unknown to me is if the heater is a "pressurised" unit or an "unpressurised" unit. The difference between these two things may be important.

Further, if your heater is in actual fact a 12kW unit, the supply cable should be a minimum of 10mm squared (copper cable), which should be protected by a maximum 63 amp circuit breaker. Again, this is only if your heater is a 12kW unit. In any case, it should be protected by an RCBO...especially if it is ten years old.

[longball53098]

My you have been busy. I hope the bathroom is all tile so it cleans and drys easy.

It would seem like the tests to this point indicate a problem with the pipe from the heater to the hot side of the tub valve? Do I have this correct? You think it is possible that this pipe has some restriction? Be it dirt or corrosion? Is the pipe steel or plastic? My guess is steel but back 10 years ago who knows!

The purpose of the test I suggested using the hose from outside directly to the hot feed pipe was to was to give you a constant pressure/flow from another known working supply that is not part of the piping that feeds the heater. My thought was every time you open the cold at the tub this caused a slow down of the cold feed to the heater and eventually shut it down. But now the test seems to indicate a restricted feed from the heater to the tub so the long hose test is not useful now.

So how about a new testing scenario?

You indicate that you have removed the mixer valve from the wall? Could you set up a temporary condition that would employ using hoses that would allow you to make the connections out in front of you? So possibly using a hose you feed the supply of hot water from the heater directly to the hot side of the valve? And of course you would need a cold supply also using a hose connection. With this temporary set up you now can test the operation of the heater and mixer valves using known working flow and pressure. This could further prove that the hot pipe in the wall is defective in some way.

As for flushing the pipe from the heater to the tub (hot supply) I would suggest a reverse flush to try to free anything that's in the pipe.

As for the lack of ground wires? Not uncommon for a house build 10 years ago. Definitely needs to be fixed. Not a safe condition.

I am shooting from the hip on these ideas I have so as before if someone sees a flaw or something really dumb I said then please point it out.

You indicate the "pipe" next to the heater is a shower rod? Are we then saying this heater is fixed to the wall up and next to the shower area of the tub in the same bathroom? So the pipes would be embedded in the same wall the valve is on? So if you had to channel into the wall the work would all be on the same wall within a meter area? Food for thought when you have to do the fix it part of this project. If the pipes are on the same wall it won't be a huge project just a medium to small one. In the photos it seems the wall may be a rendered over cement/brick wall. Most likely the pipes are embedded in the outer surface Thai style. The wall has no tile that I can see so using a typical power tool of choice the grinder all Thais have it would not take too much work to channel out the pipes in question and replace them as needed but I am getting way too far ahead. You still need to determine exactly what IS the real problem !!

Good luck with any further tests and stay dry and more importantly stay SAFE!!!!

[ZZZ]

Stupid me, just realized that since I have a good flow of water coming in via the cold water peipe, all I need do is exactly what I did before using the flexible hoses with heater out of the loop, except remove the tap so there is noweher for dirt to get stuck. And if that fails, do it in reverse i.e. connect down at the tub taps and let it shoot out the wall where it would notmally connect to the heater, etc.

this is what comes of battling the IRS, kitchen re-modelers and the hot water problem all at once...!

Anyhow will try this tomorrow and report back

Sheryl, looks like you have it narrowed down to the pipe in the wall between the heater and the tub. What you suggest to do sounds good. First you should try and snake a wire, stiff electric wire, old coat hanger, in to the wall from both ends. You will probably not get very far but with a bit of luck the blockage could be in the first bend.

Then flush the pipe from both ends as you suggest.

Failing that you could get some kind of chemical pipe cleaner, suited for the kind of pipes you have. Drain the pipe and try to pour the chemical in to the pipe from the highest point. Be careful and follow safety instructions as these chemicals can be very nasty.

Good luck

[ZZZ]

Now for what makes no sense to me:

When I disconnected the outflow hose (D) from the wall, leaving it connected to the heater and turned the power back on, I was expecting that either (1) there would be no water coming out since hot water tap still turned off (assuming that the hot water tap has to be turned on to send water through the unit; I am not really sure at what point in things the water tap comes into play) or (2) there would be a flow of hot water since, disconnected from the wall and the tap, there was now no flow resistance (assuming that the weater tap comes into play only in allowing or not allowing an outlet for the heated water).

To my surprise there was instead a low flow of cold water -- lower flow and pressure than the incoming pipe has by far but maybe a little more than I get from the hot tap when turned on. It did NOT heat up with time. So somehow, with both taps off, the incoming cold water entering via Hose A was getting over to the outflow hose D even though both taps were turned off, but either without going through the heater or with the heater elements not working. I tried turning on the cold tap in the tub to see if that affected things, no change.

Sheryl, I was checking back on earlier posts and in the above post you say that the incoming pressure to the heater was very good but out going pressure, directly from the heater NOT going through the wall pipe was very low so there still seems to be a problem in the heater?

[Sheryl]

Alas, good theory but did not pan out. With the faucet taps and heater out of the equation, there is no obstruction to flow of water through the hot pipes and it comes out with force and flow equal to that on the cold side provided the cold tap outlet is pulgged off. Opening the cold outlet causes a marked reduction in flow but this I think is to be expected given the pipe layout which is as described in both Elgan and LB's diagram.

Putting the faucet taps back into the equation slows things down a bit, understandable from looking at its valves, and maybe I could replace it with one that did not do this but I think the relative effect of having the cold on would be the same?

Now for some flow tests.

Flow into the heater = about 13 L/min with cold water not running, drops to 7.5 with cold on full force.

Flow from the heater measured directly from the hose end, not running through the faucet = about 5 L/min with cold turned off, dropping to virtually nil (droplets) if cold is one full force and around 2.5 L/min if cold is on about mid-way which is as much or more than I would need to get a comfortable temperature mix.

(BTW unlike before, water at free hose end did come out heated as one would expect. No idea why it didn’t before, maybe some transient problem with incoming voltage or pressure within the unit as a result of various things I had just done to it?)

Flow from the heater measured at the tap (i.e. putting the faucet and its valve back into the equation) = about 3 L/min with the cold off. I can't say what it is with the cold turned on since there is only one tap they flow out of but based on what I feel temperature wise I think it stops altogether.

In answer from Elgank's q, no, there is no leakage at tub when the shower valve is pulled up.

What I gather from all this and please correct me if it seems wrong:

 Although passage through the heater does greatly reduce the flow of the water (looking at the diameter of the pipes don’t see how it could do otherwise), the out flow rate with the cold turned off is the 5 L/min it is supposed to be. With the cold turned on not more than half-way it drops considerably but is still above the minimum 2.5L/min stated by manufacturer. It stops altogether fi the cold is one full force but no real reason why I'd need to do that. This is in terms of what comes down the pipe.

 The valve of the faucet tap further cuts the rate of flow, from 5L to 3 if the cold is off and from 2.5L to I suspect nil if the cold is on, or if not nil then to a level where it no longer heats it. (Based on fact that the water becomes completely cold). I suspect that the heater has some sort of flow sensor or pressure device that shuts it off when the water flow through it drops below a certain point.

o Question: is this common or do I have a weird faucet? Am I likely to find one that doesn't do this and allows, when fully open, unrestricted flow?

LB, I understand your hose test, reason I have not yet done it is that it would entail a huge hassle and purchase of additional supplies not on hand (hose, adaptors etc) and seems to me we already know that having cold on cuts the pressure of both inflow and outflow to/from heater by about half, a separate source of cold water would logically avoid this effect and I'd have a stronger flow of hot water. The only thing to be learned that is not certain is whether it would allow some degree of mixing of hot and cold. Since presumably the reason I can't mix is that the heater shuts off upon reduction of flow rate below a certain point there's a good chance it would. But what would I do with this information? Can't see an application that would not involve serious tearing apart of walls and tiles to put in new pipes etc??

In terms of options that do not entail all that, what I can think of are:

1. Get a new faucet, one which does not have the same effect of restricting flow. This one, the valves when in fully open position still narrow the lumen. Based on above tests this should at least result in a stronger flow of hot water when the cold is off, might or might not allow some mixing. From taking a bath point of view changing to 2 altogether separate taps would work best but that of course presents an issue for showering, I want to be able to take both hot baths and showers.

2. Try to rest the pressure sensor/regulator in the heater itself so that it does not shut off as readily. Not sure if this can be done nor if it would be safe or risk damage to the unit.

3. Find a way to reduce the degree to which the unit heats the water so that the result is comfortable by itself and no need for mixing with the cold. If #1 succeeds in getting me more flow this might do. Otherwise, it would still do for showering but not for hot baths (by time tub is full water has cooled off) in which case, switch this unit to say my bathroom or kitchen sink, both of which are currently unheated but where it would be nice to get consistent warn temperature of water, and buy a new water heater for the tub/shower. If I buy Stiebel, might be able to get the supplier to do both the installation and the switch of the old unit to new location.

My inclination is to do #1 first, see what happens and then if mixing still an issue, proceed to #3. Unless someone thinks that #2 can easily be done and not likely to harm the unit. Seems to me the manufacturer would have set the flow sensor/regulator for a reason?

Thoughts/reactions?

I really, really appreciate all the time you guys have spent helping me through this. Have already learned a great deal!!

[ZZZ]

Sheryl, looking at your flow rates it looks very strange that the flow from the hot water system drops by more than half when the cold water is on. That looks like your pump is very under dimensioned. What happens if you open other taps in the house? If the pump is good you should really not get much of a drop.

What kind of pump setup do you have, normally there would be a small pressure container on or just after the pump that will supply the house with enough water even if several taps are opened. This pressure container should have a lot of air in it to work properly, if all the air is gone it will not function as intended and the flow could drop the way you now see.

These pressure containers will eventually fill up with water as the air will be absorbed in the water when under pressure. You need to periodically drain the pressure container from water completely. Some pressure containers have a rubber membrane inside and then you will probably have something that looks like a bicycle tire air valve that needs to be pumped up to a certain pressure while the pressure container is empty.

Picture of the pump setup could give us an idea.

[ZZZ]

removed double posting

Edited October 21, 2009 by ZZZ

[longball53098]

Well another day and I'm anxious to hear what Sheryl will find today. Are you getting water logged yet?

From the round of tests that you did up to now I would say my ideas are no longer needed as you seem to have narrowed the flow issues to the heater. ZZZ is pointing fingers at the output of you're pump and I guess this should be checked for output under load of more than one faucet open at a time. The tub is on the second floor so maybe the pump does struggle to keep the flow constant at that height. So a flow rate test of two or more outlets from other valves might be in order.

[Sheryl]

There is no problem having more than 1 tap open, and running, for example, the sink in the same bathroom does not cause this effect. I often have multiple taps open in the house at once, if there is any drop in flow as a result it is not a noticeable one.

I haven't gone and measured flow rates but it is only when the cold tap at the tub/shower is opened that this happens to any obvious extent, which to me makes complete sense, since the water comes off the same pipe at a lower point on it. The point of entry into the water heater is a good meter higher than the the point where the cold exits.How could that not cause a drop in pressure?? Same effect as having a major leak in a pipe. Water is diverted following the path of least resistance. ????

Anyhow here are pix of it taken from vaious angles. Model is HTC-175S, 12 Amps.

I see no one has commented on the reduction in flow due to having the faucet taps in the equation. Is that really inevitable? They have ball valves which contain plastic rims that narrow the flow lumen considerably even when in completely open position, is it likely I can find a bath/shower tap unit that does not do this?

[longball53098]

Sounds like another fun time playing in the water and more answers

I agree that the pump is doing its job. I will make a guess that another valve assembly will pretty much do the same thing which is when the cold side is opened to mix with the hot that the flow rate/pressure from the hot side at it's minimal opening is not strong enough to overcome the cold side pressure and it causes the heater to shut down.

I want to recommend another type of heater may be the option. I know Stiebel makes one and most likely other brands. This type would have an electronically controlled setting that heats the water to a specific temperature and no higher or lower than the setting. So this would allow opening the hot side valve to its maximum and the water would still be only XX degrees. If hotter or cooler water from the heater is needed the setting can be changed via a remote control unit. Bear in mind these units do not come cheap. I have not researched too much beyond knowing they exist and are spendy.

I'm not sure if that is where you are headed here and more testing could be done to see if there is another fix for this problem but its seems like its coming down to the valve and the heater now.

[elkangorito]

Your unrestricted flow rate of 13 litres per minute is barely acceptable (about 3 gallons per minute) according to many websites.

With regard to flow resistance, any T pieces, elbows, taps (faucets) & the like will add resistance to the flow.

The below sites provide detail about this.

You may find the below sites usefull.

http://www.askthebuilder.com/B372_Water_Pressure_Loss.shtml

http://books.google.com.au/books?id=9UQW6v...rop&f=false

I've put together a little schematic diag of what I think is happening in your bathroom. I've used electrical theory as an anology.

flow_rates.pdf

[Sheryl]

Elkang thanks for taking the trouble to do this. I can't fully follow the diagram but I do get the overall point which is that there is a loss of pressure when water passes through the heater and again passing through the faucet tape (and I suppose again through the shower head if using it). And that when the cold is on there is a loss of pressure initially going into the heater.

I'm not sure if your diagram factors in the substantial loss of pressure from passing through the faucet valves, though? With hot on and cold off, I don't get 5L/min from the shower head or bath taps; I get 5L/min before the water passes through the faucet valve. The faucet valve reduces this to only 3L/min. Which seems like a considerable driop to me and why I wonder if a change of faucets would help. With the faucet out of the picture I can turn the cold on partway and still have some hot flow.

LB I am, of course, thinking about another heater but am concerned I might still have a flow rate problem. Issue is not only one of temperature (need to mix with cold 'coz too hot); it is also the time it tales to fill a tuub which makes a hot bath essentially impossible. A temperature controlled heater, or for that matter this heater if I can find a way to reduce it's temperature, would solve the problem for showering but not for taking a bath.

I looked up the average capacity of a bathtub and seems to be (subtracting for displacement) at least 200 Liters. Ideally one would want to fill the tub in 5 minutes which is clearly out of the realm of the possible. But even to do it in 10 minutes, would need pressure of 20 or a little more than I have before even passing through the heater.

Now I am not keen on trying to get a more powerful water pump for a lot of reasons; the one I have is quite new and works fine in all other respects; and I worry about having too much pressure on the 1st floor as with waht I currently have it is already quite a deluge whenever something springs a leak...and I don't know how much pressure the pipes can take. On the outsiode of the house and everywhere that is visible is all PVC, assume it's the same in the walls.

The idea of adding a restrictor on the cold side is interesting but seems to me that the only thing it could achieve is enabling me to get the right shower temperature, which might also be possible through other methods (e.g. disconecting one the of the heating elements to lower the degree current heater heats to and running just the hot water, or buying a new heater with a temperature control and doing likewise). Still leaves me without a hot bath! (as in, bath-tub bath, not shower).

In my travels I have stayed in scores of hotels and servcied apartments with all manner of hot water heaters and seems to me the only ones I ever found to be remotely viable for filling up a bath tub with hot water were the tank kind, and that these worked well in terms of delivering a decent flow but of course were limited by their storage capacity (I'm talking here of the wall mounted point of use ones not big tanks). So probably this is what need to get??

I don't want to toss the current heater as it was costly plus despite my having had it for 10 years has hardly been used due to the problems mentioned, so if I do get a new tank type heater I'll want to install the old one at a sink and for that would also need to get the temperature lower. Which brings me back to the idea suggested earlier in this thread that there might either (1) be somewhere in this heating unit a means to lower the temperature or (2) that this might be achievable by diconnecting one of the heating elements.

Now that you have all seen pix can anyone say if there is a likely spot that, adjusted, might lower the temperature? Or failing that, how hard is it/are there any downsides to disconnecting ioen of the heating elements? Meanwhile I am still planning to try a different faucet plus am perusing catalogues for a possible new water heater...

Thanks!

[Sheryl]

P.S. Just now finally got a reply from Stebel as follows. I had emailed them before ever starting this thread and given uop hiope of an answer but at last my message seems to have reached the right person. her answer was:

"The unit You are using has a so called "differential pressure" switch to turn on the unit. The pressure loss with this type of switch can be quite high as obviously experienced by you.

After looking over your information and data I assume you have single-lever fittings at your bath tub, which can cause the issues you are experiencing with your hot water (when you open more cold water you thereby reduce the flow of water through the heater below the switch-on amount, which causes the unit to turn off).

With only 30Amp available for the whole house it is very hard to guarantee a sufficient flow of hot water by using instant heaters. I believe in your case a storage heater would be the best solution as they require less kW input than instant heaters (although there are stand-by losses during times the storage unit is not used). Also you will not have the switch ON/OFF issue you are now facing with your instant heater.

To guarantee enough hot water for a bath tub I would suggest you consider units with no less than 80-100 liters depending on the size of your bath tub and the other demands for hot water you might have in the house."

Now I don't have a "single lever" fitting if that is what I think it is, I have 2 knobs but cioming out the same place...so maybe same-smae? Anyhow it is clear that opening the cold turns off the hot ansd she seems to be saying that is to be expected under these circumstances.

I emailed back asking her if there is a way to lower the heat setting.

[Sheryl]

These pix may help clarify what I am saying about the faucet.

This is with the vavles closed:

This is with the valves fully open. Cold and hot sides are the same in this regard.

As you can see even in the fully open position there is a white piece across the middle that substanmtially reduces flow. I had to slant the camera a bit in order for there to be enough light to see but hopefully you can get the idea.

Is this common? Am I likely to find a fitting that does not have this i.e. jas a ball valve that opens completely?

I was just able to takle a warm bath by removing the faucet and plugging closed the cold outlet. Still took a long time to fill the tub and was very wasteful; in terms of electricity sionce I had to run in only the hot in order to offset the cooling factor due to slow filling, but it did work. So confirms I think that a different fitting would improve matters bath-wise altho still far from ideal. Whether or not it would allow some intermingling of hot & cold when I shower, still don't know. Plan to see what the provincial town stocks by way of faucet fittings tomorrow....

[Mrjlh]

Sheryl,

First I thought you were having an electrical issue, so excuse me. Now I see that is not your problem. In re-reading all the posts and seeing all your pictures, I spoted a couple of things. Maybe minor but they all add up.

First, the response from Stebel is dead on. I found several articles that basically say the same thing. I'll send them in an AM to you.

What I saw and I think someones else pointed it out too, you have no check valves anywhere I could see. Either at the pump or near the heater. One that prevents anti-siphoning. At the pump you want one on the house side. Right now you rely on the pump to be the valve. Not good idea even if the pump manufacture says it's built in. Water bleeds backward and it makes the pump work harder. It also helps maintain constant pressure in the lines in the house when water flow in not required. You need one at your hot water faucet. It prevents "hot" water from re-mixing with the cold water upsetting the temperature control. Usually, you have this valve on the "cold" intake for the heater also. A good faucet has one built in by design. hopefully that's what you will find.

Other thing I saw and this is minor, was after the pump, the piping goes from 3/4" to 1" and reduced back to 3/4". Should be 3/4" all the way. Good place to put a 3/4" check valve. I think this how Thais create what they think is an anti-rattle device. Doesn't really work.

This was a tough problem to solve and I think everyone who replied tried their darnest to solve it. But Stebel has the right answer for you. Next problem is find a mixing valve that will work. \

[ZZZ]

Sheryl,

Looks like the pump is not the problem as opening other taps have no affct on the flow.

To add a restrictor to the cold water flow could possibly help you as it will then reduce the affect of the cold water slowing down the hot water flow. A thin washer with a small hole fitted where the cold water enters the faucet will do the trick.

To disconnect one of the heating elements, looks like there are two, is easy and could possibly help as you then could have the hot water tap open more for a better flow that would stop the heater flow control to shut it off. Problem is that the flow is already very low when fully opened.

Looking at the pictures of the faucet it looks like you get less than half the flow even if fully opened so that would probably be the first thing to change. Not easy to check the flow in the hardware store but bring the old one with you and by blowing in to the faucet you can get a good idea by comparing different faucets.

[longball53098]

Sheryl, It seems you may have opened a dialogue with Stiebel so maybe they can assist with a old service manual or something to help in re-wiring the heater? I wouldn't tell them what you plan to do as they may then say that they cannot help to avoid an liability issues.

[Sheryl]

Thanks all.

I also learned from some material PM'd me by MrJlh that in this type of heater the temperatuire is inverse to the flow, i.e. slower flows are hotter as they are in contact with the heating element longer. Which would explain why it has been scalding hot -- the low flow.

Mulling over elkang's post I measured flow rate at the shower head and found that it, too, was slowing things down quite a bit. It was a high quality stainless steel one with multiple options (massage etc). I substituted an el cheapo 120 baht plastic shower head, first widening its inlet as much as I could with a screw driver. Result was more than a doubling in flow rate (measuring only cold at that point). And -- get ready for this -- with that higher flow rate it was then possible to take a comfortable warm shower!!!!! I could actually mix a tiny bit of cold in without the hot shutting off plus the hot, while still hot, was no longer scalding. So a temporary solution to the shower half of the equation has been obtained. Temporary because the down side of el cheapo shower head is that it is like standing under a tap, doesn't throw the water very far or as wide as better shower heads do.

Also, where would be the best place to install it in the tub/shower? Just before where the water goes into the heater? Where it comes out? Or where?

The bath half of the equation is still unsolved but from what I jerry-rigged last night, I know that I can manage a warm bath if I can find faucet fittings that aren't so restrictive. Tried today in nearby provincial town, only 2 places had any fittings for hot and cold and these were either the same as what I have or another variant which looked like it also restricted flow. Will go to Home Pro in Bangkok in a few days to pursue further. This will also just be a temporary solution since it will still take way too long too fill tub and be unnecessarily wasteful of electricity, but OK for time being.

Clear to me that what I really need is a tank type heater as my water pressure on second floor is simply not suited to a tankless type. I'll price those when I go to Home Pro as well, but these temporary measures will suffice to let me take my time in researching the various models etc. This time around I want to be sure to get something suited to my needs and house capacities!

Many, many thanks to all who helped out on this thread. I really aprpeciate all the help and have learned a great deal. One last request for info if I may: this check valve thing. News to me. Can someone post a pix so I know one when I see one and also tell me what they are called in Thai? I will install it both at the water pump and in the bathroom as suggested. I note that my water pump runs periodically even when no water usage, presumably in order to maintain the water pressure, maybe these valves will reduce need for that.

Mucho gracias!

[longball53098]

I've lived in 3 places with water pumps now and the only time the pump operates is when there is a call for water or there is a leak. If there is a slow leak somewhere this will cause the pump to cycle to build up pressure again and then stop. Look around for a drip, drip, drip or a slow leaking toilet valve. The pump should not cycle needlessly.

[Sheryl]

LB I don't think there is any leak. It runs for just a moment i.e. maybe 20 seconds and only a few times in a day, like every 8 hours or so. Which is why I have always assumed it was just doing that to maintain the pressure and why I though maybe a check valve would help. Haven't tried it yet tho and will be a while before I do as I need a break from messing with the plumbing!

End of the hot water heater saga is this: it turns out there are 2 types of ceramic valves common in tub fittings in Thailand, the most common of which is "water save" and that is what I had, and why it restricted the flow so much. Bought one without that which the HomePro guy swore was nam leng mak ti soot, and with that installed I can now mix hot and cold OK. Overall flow rate is fine with new shower head + new fittings, tub rate still slower than one would want (4-5L/min) but bearable and the best I am likely to get with this particular heater.

In other words: there was nothing wrong with heater, pipes or hoses; the flow restriction was coming from the faucet fitting and shower head, and this particular type of heater turns off below a certain pressure. Also, the maximum pressure this heater is built to produce is not really suited to filling up a bathtub. For that, would need either a storage type heater or maybe one of the high powered tankless ones but latter would not be possible with the 30 A I currently have coming inot the house. And the tank heaters that fit on the wall seem to go only up to 30L, not enough to fill the tub all the way with hot water, and there's not really any convenient place to put a large standing tank without a major bathroom remodel.

I'll probably tolerate what I have for now and when and if there is an unavoidable need to tear open the walls where the pipes are, go solar, which is what I wish I had done to begin with!

Again thanks to all who patiently helped me through this, I learned a lot of useful things along the way.

Now I just have to repair the chipped bathtub porcelin which resulting from the old faucet fitting crashing down with a bounce as I was unscrewing it....!

[longball53098]

Well great news that you now can take nice shower. Oops on the chipped tub!

As for the pump cycling ,,,,,,IMHO the pump should only cycle when demand on the system drops the pressure to turn it on. If it cycles even once in 8 hours you are loosing pressure in the system somewhere. Either the pump's pressure tank is bleeding off pressure or there is a slow enough leak in a pipe joint or valve that it takes that long to be noticed by the pump.

I can only say that in three systems I have lived with none of the pumps cycled unless a valve was opened. In my current new house my Grundfos will not run period unless I open a valve to draw water. One hour, one day, 3 days ,only when needed.

But I am certainly no expert in this arena and one of the pump experts will set us on the correct answer I'm sure

[faifa77]

Hi guys

One thing you are forgeting about TIT. Where the hot wires are often on the neutral buss bar and the neutrals are on the breakers so when you switch off the breaker the hot is still going to the water heater. Even the main is often only 1 pole so this will not solve the situation. In addition the electricians often tie in at the meter when they run out of breakers so you turn off the main and still have a hot wire...be careful with your advice as well -intentioned as it is...electricity is very dangeous and I don't want any of you to get hurt!

Jack

and yes I am an electrician.

[Gonsalviz]

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.

I am leaning toward this theory.