help overflow from tank overflowing

[dawezo]

hi overflow in tank is overflowing, not from f&e tank, system comprises of heat only boiler, unvented cylinder, which i have just replaced yesterday because of constantly overflowing tanks. (assumed coil had split)

Water had been going up expansion into cws tank making the water luke warm ball valve has also been recently changed although this is irrelavant as the water is luke warm so that can't be the problem.

There is a pump fitted to hot water directly from cylinder supplying whole house with hot water cold feed is mains

mixer taps to all outlets and thermostatic mixer shower above bath. can't see that these are causing problem as all new and pressure is fairly equall, and that i installed pump and bathroom suite approx 1 year ago and problems only just started.

f&E tank is slightly lower than cws tank but can't alter or put expansions higher because of pitch of roof, and again it's been like this all the time so why would it be causing a problem now?

HELP im all out of options.

 

[Nige F]

Three points 1- i`m not registered for unvented, or anything else 2 Seems like some check valves are missing on various draw-off`s. 3 expect a load of abuse from RGI`s and Unvented certfied bods . I`ve been cetified myself

 

[seco services]

nige f
re-read it unvented with a cws. i think he's just getting confused.
its a vented system with a pump on the hw supply to the taps etc.


dawezo
if its a constant overflow problem then i would say you have a issue with a mixer tap or shower thats cold mains fed and hw gravity .

its passing cold to the hw as the cold is higher pressure.
shut your mains stopcock and you'll find it'll stop overflowing.

then you need to isolate each mixer in turn to locate the faulty one.

 

[picasso]

if you have mains pressure on cold and pumped on hot this will give you problems, the cold should be pumped as well, as already said it will be cold mains pressure pushing up the hot cylinder, probably through the pump.

 

[dawezo]

sorry my mistake it is vented mistype thats all.
would putting a prv on the mains and setting it to the same as the pump solve the problem? also why is this only happening now a year after the new bathroom suite and never happened before? also was'nt aware you could pump mains water?

 

[seco services]

you put a prv on and set to say 1 bar thats still higher than the hw when the pumps off.

but then when the pumps running it'll probably be lower than the hw.

 

[dawezo]

thanks seco any ideas how to get around it then hot water has to be pumped because pressure is rubbish would changing the pump and putting a could feed from cws into pump as well work? only problem with this is bathroom floor is tiled and don't think im gonna be able to alter mains to suite and change to pumped, any other options you can think of?

 

[seco services]

would be better if they where both pumped hot/cold water then you'll have even pressures.

but many are on un equal pressures and work ok.
find what one is letting by and fit a non return on the hot side to the mixer.

 

[dawezo]

would it be wise to fit non return valves to all the hot outlets or would that cause me further problems?

 

[seco services]

should by regs have non return valves on uneven pressures.
stops cat 1 mixing with cat 2 backflow protection.

or change the faulty mixer.