Hot water systems

[samran]

Hi everyone.

 

We’ve just moved into a new place and we’ve got a Siemens hot water system on the wall. It seems to know only two temperatures- boiling and cold.

 

Does anyone know how to get it a bit more spread in terms of temperature? Thinking of getting the condo electrician in,  but would like to know how this works before I ask. 

[Crossy]

What model is the heater?

 

Check that there are no flow restrictions in the water supply. Pop the hoses off the heater and check for screen filters, clean them. Clean the shower head too. More flow will mean cooler water.

 

Does the unit have a temperature knob, it's possible that the control electronics is fried (although this usually means no hot water). Fried electronics invariably means time for a new heater ????

 

[samran]

2 hours ago, Crossy said:

What model is the heater?

 

Check that there are no flow restrictions in the water supply. Pop the hoses off the heater and check for screen filters, clean them. Clean the shower head too. More flow will mean cooler water.

 

Does the unit have a temperature knob, it's possible that the control electronics is fried (although this usually means no hot water). Fried electronics invariably means time for a new heater ????

 

Here is a couple of pictures of that helps. No obvious temperatures knob. 

 

Edited October 24, 2018 by samran

[Crossy]

Ah, a 3-phase beast.

 

It's a 12kW multipoint heater intended to feed a mixer tap for a shower etc.

 

You can reduce the power a bit by disconnecting one incoming phase, but since it's likely 3-wire (no neutral) there's no opportunity to disconnect two.

 

Can you post a photo with the lid off so we can see the works please.

 

[sometimewoodworker]

 

On 10/23/2018 at 10:46 PM, samran said:

Does anyone know how to get it a bit more spread in terms of temperature? 

As crossy said you can't get a spread of temperature from that. It is always fixed, you can set it for 6kw or 8kw

so you need to use mixer taps as in Europe and the US

 

or replace the unit with a single point one

Edited October 28, 2018 by sometimewoodworker

[topt]

On 10/28/2018 at 8:20 PM, sometimewoodworker said:

 

As crossy said you can't get a spread of temperature from that. It is always fixed, you can set it for 6kw or 8kw

so you need to use mixer taps as in Europe and the US

 

or replace the unit with a single point one

I have an older smaller version of the Siemens under sinks feeding the sink and shower and even with mixer taps on the shower I have the same issue as the OP. 

 

This causes a problem if I want to increase the flow and turn the mixer handle from fully cold (say 20 past) to half past I get much better pressure but it becomes literally burning hot very quickly. I have cleaned the hoses/filters leading to and from but does not seem to make any difference.

 

Do you think this could be a problem with the original pipe set up or could I solve it by changing to a newer version (eg. like the Mazuma Redwing) of which I have one on the kitchen sink? 

It is just annoying especially when the mains pressure varies so much - and no I don't want a single point 

[sometimewoodworker]

54 minutes ago, topt said:

This causes a problem if I want to increase the flow and turn the mixer handle from fully cold (say 20 past) to half past I get much better pressure but it becomes literally burning hot very quickly. I have cleaned the hoses/filters leading to and from but does not seem to make any difference.

 

Do you think this could be a problem with the original pipe set up or could I solve it by changing to a newer version (eg. like the Mazuma Redwing) of which I have one on the kitchen sink? 

It is just annoying especially when the mains pressure varies so much - and no I don't want a single point 

In my opinion you have a couple of problems, I can offer answers to both but both involve spending.

 

the first and easiest one is your complaint of the pressure that varies greatly. Simple complete fix and I know it will work. Add a storage tank at the point that water comes into your property or with a direct supply  (if you never get water cuts then anything over 250 litre capacity will be enough) add a pump after the tank, you will then have minimal pressure change.

 

this may be a complete cure but should be your first step anyway, total cost can be well under ฿10,000

 

if after that you are still having problems with the water from a mixer tap getting to hot then the next replacement is the mixer tap as you have a cheaper unit and you need one with thermostatic control. That is probably going to be more (or extremely) difficult to find in Thailand, it is possible that some of the Häfele models have this (I haven't checked thier catalog) if so then a reasonabley easy but quite expensive fix.

 

if you have done both of these then 1st look at the pipe work and last would be a change of heater, but I don't know and I don't think that it will make much difference. The only reason it could is if the heater switch is controlled by water flow and the shower at first doesn't have enough flow to switch the heater on. If that is the case then a different heater that maintains a reservoir of hot water is probably the only fix.

Edited October 31, 2018 by sometimewoodworker

[topt]

1 hour ago, sometimewoodworker said:

Add a storage tank at the point that water comes into your property or with a direct supply  

Thanks for the suggestions.

 

Unfortunately already have tank and pump and even when the pump was working properly this was still an issue. The varying pressure doesn't seem to make any difference - IE even when it is constantly high there is still the issue with it being too hot if I turn the mixer to more than say 23 minutes past. The mains pressure when good is better than using the pump - I know get a new pump. 

 

The pipe work apart from the normal connections to the heater are buried so nothing is going to happen. The mixer just mixes which leads me to suspect that it is the way the heater operates - which was I believe the OPs original issue 

 

PS - and the heaters are at least 8 and probably more like 12 years old........ 

[Crossy]

It makes a change to have a thread on hot water that's too hot.

 

But, winter seems to have arrived, decidedly parky here in northern BKK (OK 23C), had to turn our water heater up.

 

Cue the "How do I get hotter water?" threads.

 

[sometimewoodworker]

On 10/31/2018 at 8:49 PM, topt said:

Thanks for the suggestions.

 

Unfortunately already have tank and pump and even when the pump was working properly this was still an issue. The varying pressure doesn't seem to make any difference - IE even when it is constantly high there is still the issue with it being too hot if I turn the mixer to more than say 23 minutes past. The mains pressure when good is better than using the pump - I know get a new pump. 

 

The pipe work apart from the normal connections to the heater are buried so nothing is going to happen. The mixer just mixes which leads me to suspect that it is the way the heater operates - which was I believe the OPs original issue 

 

PS - and the heaters are at least 8 and probably more like 12 years old........ 

Well getting a new pump may do nothing at all. And the age of the heater (as it's not too cold) is probably irrelevant.

 

Is your pump pressurising the complete system?  If not then a diagram will be helpful.

 

at the moment 1 or more thermostatic mixer taps/shower outlets seems to be the answer 

[sometimewoodworker]

This is an example 

 

And a better one

Edited November 2, 2018 by sometimewoodworker