Instant gas hot water and cold water pump

[MasterPlumbersKeymaster]

I have a Valliant instant gas hot water system. The cold water is pumped from a tank, ie. it’s not town water. The pressure is very good, but the pump does turn on and off continuously throughout operation. Our hot water fluctuates badly in temperature and pressure, worse the further away from the gas heater ie, the tap closest to it gives continuous hot water if turned on fully (cold water if only turned on a little), at the other end of the house the shower gives fluctuating temp and pressure – the gas heater turns on and off. It’s a normal shower head, not water restricting (we did try a restricting shower head but it made the problem 10 times worse).
Any suggestions to fix the problem – is it the pump causing the problem? Can we improve the pump or should we change the hot water system?

[Robert Stephen MortonParticipant]

Mr wenvent. what are the top & bottom pressure switch settings?
If the pressure & flow is as you say, good. you may be able to install a pressure reduction valve to just under the bottom pressure setting.
The best ones are the diaphragm type but it should be non restricting.
Bob

[SelgasParticipant]

Mmmmmmmmmmmm I have struck this problem a couple of times and have found a satisfactory cure by installing a compensating tank (actuator) after the pump which levels out the pressure developed from a water pump and stops it “pulsing”.
Let us know how you get on it is an interesting problem you have there.

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Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

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