Luke Warm Water from Hot Tap

[tyzer007]

Hello - and thank you in advance for your help on this one.

We have a Salamander Homeboost pump fitted to the mains supply to our flat. We have tanked hot water which is heated by our Valliant Ecosystem 30KW boiler. The flat has 3 bathrooms upstairs, 1 downstairs and kitchen taps.

When the Homeboost pump is on, we check the temp coming from the tank (37C) and when we disconnect the hot tap from the kitchen mixer tap and check the temp it is 16C. The same is true for one of the upstairs bathrooms. The problem seems worse for the bathtub where there are dedicated hot and cold taps compared to the mixer tap for the shower.

When the pump is not turned on, the temperature in the kitchen and affected bathroom is Ok - but not as good as the hot temperature from the other 3 bathrooms.

We think that the issue may be a mixer tap that is allowing the hot and cold to intermingle. But we don't know how to trace this to identify for sure.

According to Thames Water we are in a Pressure Managed area which means our water pressure is fine daytime, but that in the evening Thames drops the pressure and then we need a boost.

Any help is diagnosing this problem is much appreciated. Thank you!

 

[Riley]

WhT sort of hot cylinder have you got. Any pics

 

[Burger]

Have you changed any of the taps recently? Had any work/modifications done recently?

 

[tyzer007]

WhT sort of hot cylinder have you got. Any pics

MegaFlow - CL210

We know that there is a flow balance valve attached. We initially thought it had failed so have replaced that - but with no change.

thank you!

 

[tyzer007]

Have you changed any of the taps recently? Had any work/modifications done recently?

We have had a new boiler installed (plumber who did the install came back - but was unable to diagnose the issue). We changed one of the upstairs shower mixer taps - professionally changed.

 

[Riley]

Unlikely to be related but no one in their right mind should’ve fitted a megaflow to 12litres a minute pumped incoming.

 

[Riley]

The only way to test is to isolate the cold on each mixer and see if it affects your problem

 

[tyzer007]

Unlikely to be related but no one in their right mind should’ve fitted a megaflow to 12litres a minute pumped incoming.

Thanks for this. Can you explain a bit more? We attached the HomeBoost pump to the mains so that there would be the same pressure going to both hot and cold.

 

[tyzer007]

The only way to test is to isolate the cold on each mixer and see if it affects your problem

Due to the nature of the fittings it is not possible to isolate. (Builder was not the best - always cutting corners.)

There are isolating valves in the kitchen - but nowhere else. Not even in the bathroom sinks. And due to the nature of the shower mixer valves, we can remove the cartridges - but can't actually shut them off.

I guess my question is: "Do you think the most likely situation is that one of the mixer valves is the culprit?" - Because if that is the case I think I can identify which one based on the way the pipes flow.

In other words - The cold and hot have already mixed by the time they get to the kitchen and there are only 2 taps between the tank and the kitchen.

Again - many thanks.

 

[Riley]

Thanks for this. Can you explain a bit more? We attached the HomeBoost pump to the mains so that there would be the same pressure going to both hot and cold.

The Homeboost pump would give you a maximum of 12lpm as water regs prevent them giving you more. On that basis I would never in a million years be fitting an unvented cylinder as the flow rate is not sufficient.

 

[Riley]

Due to the nature of the fittings it is not possible to isolate. (Builder was not the best - always cutting corners.)

There are isolating valves in the kitchen - but nowhere else. Not even in the bathroom sinks. And due to the nature of the shower mixer valves, we can remove the cartridges - but can't actually shut them off.

I guess my question is: "Do you think the most likely situation is that one of the mixer valves is the culprit?" - Because if that is the case I think I can identify which one based on the way the pipes flow.

In other words - The cold and hot have already mixed by the time they get to the kitchen and there are only 2 taps between the tank and the kitchen.

Again - many thanks.

I really hope I’ve misunderstood but you are saying your hot and cold mix before they reach the kitchen?? Hopefully that is via a tmv and not appalling piping??

The only way you are going to know for sure is to fit iso valves. I wouldn’t want to be changing taps on guess work

 

[tyzer007]

Below are photos of the shower mixer valve - with cover removed.

When we put a hand on the mixer with cover removed and turn on the sink tap we can feel (what we think is) water flowing through the mixer. I am guessing that there shouldn't be any water flowing through the mixer when the shower is off. - right?

 

[tyzer007]

I really hope I’ve misunderstood but you are saying your hot and cold mix before they reach the kitchen?? Hopefully that is via a tmv and not appalling piping??

The only way you are going to know for sure is to fit iso valves. I wouldn’t want to be changing taps on guess work

Sadly - you have NOT misunderstood

We took the sink and isolated the cold and just had the hot open. The temperature of the water leaving the boiler was 37C - by the time it got to the kitchen tap it was 16C - The only way that could happen was if there was mixing somewhere along the way.

Appalling piping? With this builder it's possible! (but I don't think so)

 

[Riley]

I think my friend you need to enlist a plumber. Builders build plumbers plumb

 

[SimonG]

A passing or missing check valve.

All sounds a bit heath Robinson.

 

[tyzer007]

I think my friend you need to enlist a plumber. Builders build plumbers plumb

LOL - Understood
What I meant was, "The builder" as in the company who employed builders and plumbers... most of which were underpaid...

 

[Stu-B]

Get them back if it’s not right

 

[Riley]

Sadly - you have NOT misunderstood

We took the sink and isolated the cold and just had the hot open. The temperature of the water leaving the boiler was 37C - by the time it got to the kitchen tap it was 16C - The only way that could happen was if there was mixing somewhere along the way.

Appalling piping? With this builder it's possible! (but I don't think so)

This is all sounding wrong. Your water isn’t heated in the boiler it’s being heated in the cylinder??

 

[tyzer007]

This is all sounding wrong. Your water isn’t heated in the boiler it’s being heated in the cylinder??

The water is heated through the boiler (plus we have an immersion heater)

My message above was not accurate. What I meant to say was that the water leaving the tank (after being heated via the boiler) is 37C. When I check just the hot supply (isolate the cold) at the kitchen sink it’s at 16C making me think that the cold has mixed with the hot before it gets to the kitchen.

Sorry for my sloppy message

 

[moonlight]

Has someone checked the non return in the shower? back flow issue

 

[Riley]

The water should be leaving the hot water cylinder at a higher temp than 37°c your system has either not been set up correctly temp wise or you have cold hackfeeding. The only way you are going to diagnose is to isolate micers

 

[tyzer007]

The water should be leaving the hot water cylinder at a higher temp than 37°c your system has either not been set up correctly temp wise or you have cold hackfeeding. The only way you are going to diagnose is to isolate micers

Thank you.

 

[tyzer007]

Has someone checked the non return in the shower? back flow issue

I also believe it to be a backflow issue. Will get someone to check. I assume the non return would be built into the cartridge. Right?

 

[moonlight]

I also believe it to be a backflow issue. Will get someone to check. I assume the non return would be built into the cartridge. Right?

It might be behind the shower valve depending on what shower you have. If you can isolate the shower valve you may have you answer. Unfortunately some of the cheap mixer taps can also create the same problem. If its the shower you may be able to just replace the front section.

 

[tyzer007]

It might be behind the shower valve depending on what shower you have. If you can isolate the shower valve you may have you answer. Unfortunately some of the cheap mixer taps can also create the same problem. If its the shower you may be able to just replace the front section.

Thank you!