Discuss Salamander Homeboost, Hot water coming out of cold tap in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

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Hello

I have a Vaillant Ecotec Plus 835 with a Salamander Homeboost pump fitted to the mains supply underneath the boiler.

If I switch on the cold tap first I get cold and if I switch on the hot I get hot, the booster kicks in but doesn’t switch off, but..

If I switch on the hot tap first the booster fires; does not switch off when I close the tap, then if I open the cold tap hot water flows?

If I close one of the isolation valves the pump stops as expected, and if I switch the pump off completely the taps work correctly.

My gas engineer says it’s bizarre and can only suggest replacing the pump, Salamander say they don’t think there is anything wrong with the pump as it stops when the isolation valve is turned. And neither can understand why hot would come out of the cold!?

Any suggestions would be appreciated!

Thank you
David
 
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"If I close one of the isolation valves the pump stops as expected, and if I switch the pump off completely the taps work correctly."

With this info, Id say try changing the pump.
 

Riley

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Get salamander in if they’re sure nothings wrong
 

Riley

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They will still offer a repair service
 

ShaunCorbs

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A

Aire

Id agree with salamander on this one. If the pump stops when isolated, that proves the pumps flow/pressure switches work.

Where in relation to the stop tap is the home boost fitted?

I'd also be asking your installer why he's fitted an 835 which is capable of 14ltm of hot water delivery, when the home boost is restricted to 12ltm.
 
OP
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Id agree with salamander on this one. If the pump stops when isolated, that proves the pumps flow/pressure switches work.

Where in relation to the stop tap is the home boost fitted?

I'd also be asking your installer why he's fitted an 835 which is capable of 14ltm of hot water delivery, when the home boost is restricted to 12ltm.
 
OP
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Someone has suggested that maybe one of my mixer taps or shower thermostatic controls could be worn and allowing cold into the hot so when the hot is switched off cold could still be sleeping through..?
 
OP
D
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Id agree with salamander on this one. If the pump stops when isolated, that proves the pumps flow/pressure switches work.

Where in relation to the stop tap is the home boost fitted?

I'd also be asking your installer why he's fitted an 835 which is capable of 14ltm of hot water delivery, when the home boost is restricted to 12ltm.
The booster is fitted 1m below the isolation valve and boiler.

Ground floor kitchen tap doesn’t get as hot as 2nd Floor bathroom?

The pump is fitted because my 3rd floor shower struggles with pressure, Ground Floor is adequate.
 
A

Aire

So the home boost only feeds the hot water? To have installed this you must have poor cold mains flow/pressure? Was the static/dynamic pressure and flow rate tested before installing the pump?
 
OP
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So the home boost only feeds the hot water? To have installed this you must have poor cold mains flow/pressure? Was the static/dynamic pressure and flow rate tested before installing the pump?
Yes, And has been installed for three years with no dramas.
I don’t know whether the pressures and flow rates were tested prior to installation, but I asked for it to be installed to help with my top floor shower.
 

Mastermixlee

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With only hot water being fed from the pump If there is a mixer that is passing it is possible that the pump pressure when running is enough to force through the passing mixer thus keeping the flow switch activated. But when under standing pressure not enough to operate the flow switch in the pump.

Which would explain the hot water Coming through the cold tap too. The boosted pressure hot would be flowing through a passing mixer and forcing down the cold pipework.

So if possible to turn off isolation valves to mixer taps to identify which one is at fault then go from there.

And depending on system config I'd consider putting check valves on cold feeds to taps too.
 
OP
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With only hot water being fed from the pump If there is a mixer that is passing it is possible that the pump pressure when running is enough to force through the passing mixer thus keeping the flow switch activated. But when under standing pressure not enough to operate the flow switch in the pump.

Which would explain the hot water Coming through the cold tap too. The boosted pressure hot would be flowing through a passing mixer and forcing down the cold pipework.

So if possible to turn off isolation valves to mixer taps to identify which one is at fault then go from there.

And depending on system config I'd consider putting check valves on cold feeds to taps too.
Thank you for your reply. Much appreciated.
Will give it a go and get back to you
 
A

Aire

I Agree with mastermixlee and is the reason for asking where the pump was located. The manufacturer do recommend that when using their home boost to solely feed the hot water supply, non return valves should be fitted to mixer taps showers as the static/dynamic pressures most likely won't be equal.
 

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