Thermostatic Shower Issue with Cold Water Overpowering the Hot?

[Alfie_Huntingdon]

Hi Guys

I have been struggling with an issue with the two showers in my new house.

Essentially they never get hot enough (lukewarm at best) unless you turn a nearby cold tap on full after which it gets nice and hot so it feels like the cold water is overpowering the hot within the thermostatic valve in the shower. I've taken the showers themselves apart numerous times, including replacing the wax thermostat, but it had no change on performance.

I've searched this forum and can't see any directly comparable issue.

The water system is set up as follows:
Cold side - cold water tank in the loft feeds into a Salamander twin shower pump and then into the showers (Ultra - Hudson Reed SNINASF control unit).
Hot side - a hot water tank (filled via the loft tank) which then feeds into a Salamander twin shower pump and then into the showers (Ultra - Hudson Reed SNINASF control unit).

I see two options to try and resolve it:
1. Replace the shower valves - although I can see nothing wrong with the existing and will end up costing c. £200.
2. Install some sort of resister on the cold water side either before or after the pump.

Any thoughts or alternatives suggestions would be greatly appreciated!

 

[Exedon]

How is hot water feed to pump connected to hot water cylinder?
Picture of pump and its pipework and connection to cylinder would be useful.

 

[HERTS P&D]

Fit a one way check valve on the pump outlet on the hot side. Even though the shower and pump should already have them in place.

Andy

 

[Alfie_Huntingdon]

How is hot water feed to pump connected to hot water cylinder?
Picture of pump and its pipework and connection to cylinder would be useful.

Photo of the pump attached. The cylinder is covered by insulation but I can take it off if you think that would be useful?

 

[Alfie_Huntingdon]

Fit a one way check valve on the pump outlet on the hot side. Even though the shower and pump should already have them in place.

Andy

Interesting that you think it is not enough flow from the hot side rather than too much from the cold?

When I run both hot a cold taps together in a sink for example there is a good flow from both when the pump is on which made me discount the idea.

 

[HERTS P&D]

You don't have a twin pump!

Andy

 

[Alfie_Huntingdon]

You don't have a twin pump!

Andy

Its a Salamander Pump ESP 100 - the cold water outlet is hidden in the photo.

 

[HERTS P&D]

Yep, my mistake.

Andy

 

[Alfie_Huntingdon]

No other suggestions then? Looks like I will need to try a replacement shower valve. The only other part that looks like it would go wrong is one of the springs. Which seemed fine when I took them apart.

 

[HERTS P&D]

Fit a one way check valve on the pump outlet on the hot side. Even though the shower and pump should already have them in place.

Did you try this?

Andy

 

[Alfie_Huntingdon]

Did you try this?

Andy

Sorry I should have come back to you on this. I believe the showers have the valves built in: https://www.showerdoc.com/ultra-3-4-dual-control-valve-short-elbows-and-flanges-chrome-sa30918s

Can these fail/are they worth replacing before the more expensive cartridge?

 

[oldbuffer]

1. They can fail.
2. Do as Herts P&D suggested, fit a one way check valve in the hot feed from the pump. Cheap and cheerful and may well fix these issue. If not you won't have spent much on the diagnosis.

 

[Alfie_Huntingdon]

1. They can fail.
2. Do as Herts P&D suggested, fit a one way check valve in the hot feed from the pump. Cheap and cheerful and may well fix these issue. If not you won't have spent much on the diagnosis.

So something like this running out of the pump?

https://www.industrialwaterequipmen...ale-x-male/mini-check-valve-female-x-male-34/

From the pump manual I note it states: " NON-RETURN VALVES MUST NOT be fitted in the discharge pipework between the pump outlets and system outlets unless specified by Salamander"

Source: https://www.salamanderpumps.co.uk/uploads/downloads/Centrifugal Installation Guide - Nov 2015.pdf

But I'm assuming it will still be okay?

 

[Madrab]

I presume the pump is in the attic, the CWSC in the attic and the HW cylinder downstairs? Is there an anti-gravity loop? Pumps in the attic can always be susceptible to problems, it really isn't the best place for them to be situated.

Is this a new issue or has it always been this way? Is there an essex flange in the cylinder? Both feeds supplied by 22mm all the way and the same with the supplies to the showers?

 

[Alfie_Huntingdon]

I presume the pump is in the attic, the CWSC in the attic and the HW cylinder downstairs? Is there an anti-gravity loop? Pumps in the attic can always be susceptible to problems, it really isn't the best place for them to be situated.

Is this a new issue or has it always been this way? Is there an essex flange in the cylinder? Both feeds supplied by 22mm all the way and the same with the supplies to the showers?

You might be on to something here. You are correct the pump is in the attic, above the HW cylinder which is on the floor below and about the same height as the bottom of the cold water tank. All the pipework looks to be 22mm to me.

I moved into the house a year ago and it has never worked correctly without the cold water tap on. I know the pump was installed prior to the previous owners who moved in 2016 - so it has been there a while. The previous owners didn't really use the showers and maybe the lack of heat is part of the reason why!

The attached screenshot in the Salamander installation guide shows our setup and says "No Stop Essex MUST be used with an anti-gravity loop at least 200mm in depth".

See the photos. There is an anti-gravity loop but only 100mm - there is not much room for any more. I'm not sure if there is an Essex flange installed.

I see that Salamander has its own non return valve so that should be worth a go as a first port of call and if the valves on the showers themselves have broken: https://www.showerspares.com/search/salamander-non-return-valve-nrv/