Hot water supply to shower and kitchen luke warm. Temporarily no cold supply.

[Danielalford22]

We recently had a new comni boiler fitted.
During the install we realised we had an extra pipe heading to the loft we assumed was related to the old tank

We had it cut off.

It seems this was the cold water feed to our shower.

As a temporary solution we have adjusted the hot water temperature on the boiler to just use the hot tap on the shower.

However even increasing as high as 60 degrees its only luke warm with the tap set fully to hot. Same story in the kitchen.

The tap in the bathroom sink however is piping hot.

Will running a new cold water feed to shower fix this or do I have a bigger problem?

Thanks all

 

[CountryFan]

What has your installer said? Sounds like possibly crossed pipes or you need this cold feed. Was the cylinder removed? Which make/model of combi?

 

[Madrab]

Is the kitchen sink a mixer? Basin separate taps?

It's possible there is cold water crossflow happening as the shower hot feed is no longer balanced. I would suspect that re-instating the cold feed to the shower may sort it out.

 

[denso13]

Will running a new cold water feed to shower fix this

Probably, some just won't work with only one pipe connected, hot or cold.

 

[Danielalford22]

Is the kitchen sink a mixer? Basin separate taps?

It's possible there is cold water crossflow happening as the shower hot feed is no longer balanced. I would suspect that re-instating the cold feed to the shower may sort it out.

All 3 areas are actually mixers but non thermostatic. Cold feed still going to the kitchen sink but same problem there

 

[Danielalford22]

Is the kitchen sink a mixer? Basin separate taps?

It's possible there is cold water crossflow happening as the shower hot feed is no longer balanced. I would suspect that re-instating the cold feed to the shower may sort it out.

All 3 areas are actually mixers but non thermostatic. Cold feed still going to the kitchen sink but same problem there.

Bath sink all good
Shower warm water only despite only hooked up to hot feed
Kitchen warm water only and cold connected to both.

Likely the cold feed back to shower will be from another area save having to lift floorboards just hoping this deals with the issue

 

[Danielalford22]

What has your installer said? Sounds like possibly crossed pipes or you need this cold feed. Was the cylinder removed? Which make/model of combi?

Cylinder long gone before this install.
Boiler is Navien NCB 300 30kw

Producing perfect hot water in bathroom sink. Just warm now to kitchen and shower (which only has hot feed connected currently)

 

[Johntheo5]

Does the HW pipe at the Boiler only feel as warm as the temperature in the kitchen and at the shower,, what is the temperature set to?

 

[Danielalford22]

Does the HW pipe at the Boiler only feel as warm as the temperature in the kitchen and at the shower,, what is the temperature set to?

Increased all the way up to 60 now. Piping hot in bathroom sink when switched fully to hot. Shower and kitchen sink only warm doing the same

 

[Johntheo5]

Yes, but does it feel like 60C just leaving the boiler, does the boiler display the DHW temperature, I'm thinking that there might be some X over from a cold supply somewhere because if its leaving the boiler at 60C or so and its only lukewarm in the kitchen/shower then there must be some cold water mixing somewhere?

 

[Danielalford22]

Yes, but does it feel like 60C just leaving the boiler, does the boiler display the DHW temperature, I'm thinking that there might be some X over from a cold supply somewhere because if its leaving the boiler at 60C or so and its only lukewarm in the kitchen/shower then there must be some cold water mixing somewhere?

Certainly hot leaving boiler. I also considered cross over. But never had this issue when the shower had a cold water feed. That feed is temporarily gone and now the hot feed is onlt luke warm in 2 locations. It's a real puzzle I have to say

 

[denso13]

But never had this issue when the shower had a cold water feed.

Reinstate this first and see what happens, you can then decide from there.

 

[Johntheo5]

Certainly hot leaving boiler. I also considered cross over. But never had this issue when the shower had a cold water feed. That feed is temporarily gone and now the hot feed is onlt luke warm in 2 locations. It's a real puzzle I have to say

Try putting the shower to fully cold and on full. See does that improve the other two.

 

[Madrab]

If the water coming out of the boiler is as hot as it should be and at least one outlet is getting that temp of hot water and there is no cold feed to the shower then there's no way for the water exiting the shower to be cooled down. Therefore there has to be a cold water crossflow and it's mixing into the hot supply before or as it gets to the shower/kitchen.

Once the cold is re-instated I would guess it will return to normal as the supplies will be balanced again.