Hot Water Only Warm in Bathroom

[xoxo]

Hi there

I moved into a flat recently which uses a HIU for hot water and heating.
I found that in the bathroom there is only luke warm water coming from the basin mixer tap and the thermostatic shower mixer.
The kitchen is fine however so that tells me the HIU and water coming out is fine as kitchen is ok.
If there is 2 hot water feeds in the bathroom one for basin and one for shower then what could the issue be?
Would changing the blender valve under basin not have any effect on shower?

Thanks

 

[Madrab]

You may find there is a TMV (thermostatoic mixing valve) on the supply to the bathroom and then splits to the basin and shower. If that's the blender unit under the basin you are talking about then it may just need adjusted.

If it's rented though I'd let the landlord know as that may be set specifically to stop scalding and may needs adjusted for your needs, post a pic of the blender unit.

 

[xoxo]

You may find there is a TMV (thermostatoic mixing valve) on the supply to the bathroom and then splits to the basin and shower. If that's the blender unit under the basin you are talking about then it may just need adjusted.

If it's rented though I'd let the landlord know as that may be set specifically to stop scalding and may needs adjusted for your needs, post a pic of the blender unit.

Hi
Is it normal to have one feeding both basin and bath if you have a thermostatic mixer shower? As that has its own thermostatic element that controls temperature.
Reason why I posted this is the developer of the property says there are 2 different feeds going into bathroom from HIU, one for basin which has a TMV and then another to the shower. If thats true then the basin TMV wont affect shower and no one seems to know what else it could be. Any ideas?

 

[Madrab]

You're right, if that's the case then the thermostatic mixing valve (TMV) for the basin shouldn't affect the shower. The test would be to turn up the TMV for the basin and check it heats up and then see if the shower heats up.

If the shower has a TMV2/3 rated cartridge then it shouldn't need an inline TMV, if it isn't then it may do to meet standards. It may be that the shower needs calibrated, can you click the shower mixer and turn it beyond the 38deg limit and does it get any hotter? If it doesn't then there is an issue somewhere in the supply to the bathroom and they need to come in and sort it. What make/model of HIU is it?

 

[xoxo]

You're right, if that's the case then the thermostatic mixing valve (TMV) for the basin shouldn't affect the shower. The test would be to turn up the TMV for the basin and check it heats up and then see if the shower heats up.

If the shower has a TMV2/3 rated cartridge then it shouldn't need an inline TMV, if it isn't then it may do to meet standards. It may be that the shower needs calibrated, can you click the shower mixer and turn it beyond the 38deg limit and does it get any hotter? If it doesn't then there is an issue somewhere in the supply to the bathroom and they need to come in and sort it. What make/model of HIU is it?

The Mixer is a Hansgrohe Thermostatic Mixer with 3 outputs, the basin mixer tap is Hansgrohe also and the HIU is Evinox.
Yes I tried the button to turn it further. Did not help. The developer thinks its not the supply to bathroom as the pressure and heat level of the water leaving the HIU is fine and its a small apartment where the HIU is across the hall to the bathroom so there should be nothing else between the bathroom and HIU.
Could it be a very simple thing and the max temp set in the TMV under basin and the Shower mixer was set too low but the previous people did not find it too cold? Its 5 year old flat so not very old and it does look like someone previously accessed the TMV under basin so maybe they decreased the temp as someone found it too hot etc.

 

[Madrab]

That's why I was asking about the shower, the thermostatic temperature control of the shower that has the safety stop should get hotter if the HW into it is hotter, when you turn that up. If it doesn't then the supply isn't hot enough, if you see what I mean.

If it was me I'd be tracing things back and opening up pipe connections and testing the water temps at different stages, starting at the outlets. Only real way to be sure TBH

 

[Johntheo5]

As above, the first thing is to compare the HIU temperature at the kitchen mixer with the HIU temperature at the bathroom mixers.

 

[xoxo]

the HIU temp when the basin tap is on was around 51 to 50 degrees.
I do know that the mixer I have has a control of the hot water temp so you can adjust max hot water level even after you press button to take higher so I am thinking the basin TMV and the thermostatic control in shower both are set too low.

 

[Deleted member 267285]

Cold could be passing? I would isolate the cold feed under the HIU for the hot water, open the hot tap at the basin and see if any water comes out.

 

[Johntheo5]

Presume temperature leaving the HIU before any mixer(s) should be 60C, also this will probably reduce with very high DHW demands.

 

[xoxo]

Cold could be passing? I would isolate the cold feed under the HIU for the hot water, open the hot tap at the basin and see if any water comes out.

When the hot water valve is turned off at HIU and you turn on the hot water tap then no water comes out and if you change to cold then cold water comes out.

Presume temperature leaving the HIU before any mixer(s) should be 60C, also this will probably reduce with very high DHW demands.

Well kitchen is fine so that should elimate the water temp before and after HIU.

 

[Johntheo5]

When the hot water valve is turned off at HIU and you turn on the hot water tap then no water comes out and if you change to cold then cold water comes out.

Well kitchen is fine so that should elimate the water temp before and after HIU.

the HIU temp when the basin tap is on was around 51 to 50 degrees.
I do know that the mixer I have has a control of the hot water temp so you can adjust max hot water level even after you press button to take higher so I am thinking the basin TMV and the thermostatic control in shower both are set too low.

Is the 50/51C the temperature before the basin mixer?,
Can you turn off the cold water supply to the bathroom mixers and see what the outlet temperatures are then, turn the shower temperature control up fully. there may be a override button on it.

 

[xoxo]

Is the 50/51C the temperature before the basin mixer?,
Can you turn off the cold water supply to the bathroom mixers and see what the outlet temperatures are then, turn the shower temperature control up fully. there may be a override button on it.

No the 50/51 was what the Evinox engineer measured via his monitoring system while the bathroom basin tap was open. So was temp when it left the HIU.

I dont have anything to measure temp at the outlet at the moment.
I may try taking off the temp control handle off the mixer and adjust the temp valve inside the mixer to see if it goes any higher.
If it does and it fixes it then the issue was the setting for max temp in both shower mixer and basin valve was set too low.
Issue is I only moved in 2 weeks ago so no idea what the temp of water was like before with others living here. so either its always been like this and they didnt care or it was adjusted and made lower by someone. Its only thing that makes sense as like people have said the basin TMV wont have anything to do with the thermostatic mixer as that has its own temp control so does not need a blender valve.

 

[Johntheo5]

If the temperature leaving the HIU is still 50/51C then that should be adequate to give at least 45C after the bathroom basin TMV if its set to this temperature, can you shut off the cold water to the kitchen and bathroom and just feel the outlet from the basin tap, if the HIU outlet is 50/51C and the basin TMV setting is say 38/40C then you will get no water from the basin tap , if you do it means that the HIU outlet temperature isn't 50/51C, but if you still (and you should) get hot water from the kitchen tap then it obviously is the bathroom basin TMV and shower TMV that are set too low.

 

[xoxo]

If the temperature leaving the HIU is still 50/51C then that should be adequate to give at least 45C after the bathroom basin TMV if its set to this temperature, can you shut off the cold water to the kitchen and bathroom and just feel the outlet from the basin tap, if the HIU outlet is 50/51C and the basin TMV setting is say 38/40C then you will get no water from the basin tap , if you do it means that the HIU outlet temperature isn't 50/51C, but if you still (and you should) get hot water from the kitchen tap then it obviously is the bathroom basin TMV and shower TMV that are set too low.

Will try that tomorrow if I can find a step ladder as its quite high up on top of the HIU haha