C/H header tank feed pipe pushing hot water into tank

[RON]

Hi all
Not actually name Ron but i am using my late uncles name as i did my apprentiship with him back in the late sixties. I have not worked as a plumber for a number of years at least 30 years but still enjoy the odd job for family. The problem below is happening at work and is in a two storey building, boiler ground floor cylinder ground floor and header tank in the loft of a two storey building.

Hot water is Gravity fed, heating is pumped system.header tank is filling up via the feed pipe and the water is hot, and no water appears to be coming out of the expansion pipe. The rate of overflow is probably about a litre per 4 hours

Pump on middle setting. No other problems with system. Only appears to happen when the heating is on, but will check tomorrow to see if it happens when on hotwater only.

Any suggestions gladly appreciated

cheers

John alias Ron

 

[ajs heating]

if it a gravity system and pumped heating you won't be able to get heating on its own only if wired as a c plan.
if not you will get either hw only or hw/heating.
is the heating f/e tank lower than the cws tank for the hot water ?

1, either a split coil in the cylinder.
2 blockage in the pipework useally around the fed/vent pipe area.

has it got an air seperator on the vent/feed pipe?

try turning the pump speed down to min.

need some more info.

 

[fuzzy]

but aj, if the boiler only on without pump then surely you can get HW only? you cannot get heating only , have i missed something or did you type it wrong?

 

[ajs heating]

fuzzy where do you see the mistake ? i've read it and can't point it out

i 've put you can get hw on its own.

>if not you will get either hw only or hw/heating.
(programmer set to hw) (programmer set to hw/heating)


the only way you can get heating on it own is if wiring as a c plan with a zone valve.

just that explain it better? correct me if im wrong

 

[fuzzy]

my fault aj, i read it the wrong way round!
your right

 

[ajs heating]

had me confused then.

 

[RON]

Hi and thanks for replying

You are correct it is h/w only and h/w +heating

The heating header tank and the cold water storage tanks are the same level (both sitting on joists)

Will try turning the pump down.

I will also check the overflow situation in the h/w only mode, as it seems worse when the heating is on.

I will post the outcome next week

thanks again

 

[ajs heating]

>The heating header tank and the cold water storage tanks are the same level (both sitting on joists)

yes but the water levels in the tanks willbe different, the cws storage should be higher than the f/e for the heating.

1, try turning the pump down to min. see what happens.

2, shut the gate valve to the hw cylinder from the cws tank in loft.
does it stop then ?

 

[RON]

Hi AJ

The pump has now been turned down but as yet I have not run H/W and C/H together. The H/W only has been running and the C/H header tank is continuing to overflow. It appears to overflow more when the boiler kicks in (obvious really i know). I will run the heating in the morning and see what happens

Ron

 

[RON]

Hi AJS

The coil has gone as you suggested. Thanks for all your help.

Ron

 

[ajs heating]

hi ron

how did you sus that in the end ? did you do as i said and shut the gate valve and the water stopped flowing into tank.

 

[RON]

Hi AJS

Yes I turned off the valve and the leak stopped. Another sign was that the water in the c/h header tank was very clear, which I think would be a good indication that the header tank is being filled from the domestice cylinder.

Thanks again.
Ron