bit of a werid one

[ShaunCorbs]

bit stumped

pics below of how its piped up









right got called out no heating turned out 2 port valve was faulty (the one you can see pic 2)

the problem/head scratcher is

turned heating on all fine and turn hot water on and starts pump over

turn hot water off and stops (pumping over)

the only reason i can think of is cylinder coil split ??????

thnx guys and gals
shaun

 

[Nick6588]

Or coil is blocked up???

 

[ShaunCorbs]

Or coil is blocked up???

but that wouldnt cause it to pump over as it would just go through the heating circuit ?

 

[village idiot]

For a start, how long have they had the problem? Seems like a design issue??

 

[Nick6588]

Were both 2 ports open? Does it pump over on hot water only? Or just when both are open?

 

[ShaunCorbs]

For a start, how long have they had the problem? Seems like a design issue??

dont have a clue (old dear)

 

[ShaunCorbs]

Were both 2 ports open? Does it pump over on hot water only? Or just when both are open?

just in hot water

turn heating on fine

turn how water on pump over

turn hot water off (leaving heating on) doesnt pump over

 

[village idiot]

dont have a clue (old dear)

It's the first thing I would have asked her. And after the answer, next question will be: Has any work been done recently to the heating circuit?

 

[ShaunCorbs]

It's the first thing I would have asked her. And after the answer, next question will be: Has any work been done recently to the heating circuit?

she doesnt know as tanks in loft and no work has been done in 8 years since new boiler

 

[stevetheplumber]

split coil would be constant its obviuosly pumping over probably bad design i would try a higher vent pipe first as that looks like it barely clear the tank im guessing its a bungalow with low head

 

[ShaunCorbs]

split coil would be constant its obviuosly pumping over probably bad design i would try a higher vent pipe first as that looks like it barely clear the tank im guessing its a bungalow with low head

cant impossible its about 1/2 foot above tank touching felt underside

 

[village idiot]

I still think it's a design fault? How about changing the pump speed to a lower speed and see what happens?

 

[ShaunCorbs]

I still think it's a design fault? How about changing the pump speed to a lower speed and see what happens?

its on two but that wouldnt explain why it would only do it in hot water not heating tho

if it was pump speed it would be pumping over in heating as well?

 

[SimonG]

Wasn't changed when new boiler was installed. Pump will be going straight through and pumping over.

Could try turning down pump speed or stick a gate valve on the hot water circuit to increase the resistance.

It's one of the reasons that when I swap boilers and go s plan I use two pumps. Hot water on 1, heating generally on 3.

 

[ShaunCorbs]

Wasn't changed when new boiler was installed. Pump will be going straight through and pumping over.

Could try turning down pump speed or stick a gate valve on the hot water circuit to increase the resistance.

It's one of the reasons that when I swap boilers and go s plan I use two pumps. Hot water on 1, heating generally on 3.

sorry mate you have lost me

 

[SimonG]

Normally cold feed and expansion are on the hot water gravity primaries. Well on an old 4 pipe boiler. New boiler goes in and they just stick the 2 port on the hot water flow and t into boiler flow, rather than adapting the feed and expansion to suit the new system.

Could be waffling for England tho without seeing it first hand

 

[ShaunCorbs]

Normally cold feed and expansion are on the hot water gravity primaries. Well on an old 4 pipe boiler. New boiler goes in and they just stick the 2 port on the hot water flow and t into boiler flow, rather than adapting the feed and expansion to suit the new system.

Could be waffling for England tho without seeing it first hand

was only a two pipe boiler before (oil)

 

[SimonG]

Well that's that one then. Bet its been doing it for years.

Cap expansion and tee into cold feed. Turn it into a low head feed.

 

[ShaunCorbs]

Well that's that one then. Bet its been doing it for years.

Cap expansion and tee into cold feed. Turn it into a low head feed.

yea just phoned her up and asked does she use the hot water setting on prog and she said no uses her immersion

and you mean combine the expansion and feed?

 

[SimonG]

yea just phoned her up and asked does she use the hot water setting on prog and she said no uses her immersion

and you mean combine the expansion and feed?

Aye..

 

[stevetheplumber]

cant impossible its about 1/2 foot above tank touching felt underside

so run up the rafter away from the eaves and back down

 

[Best]

Expansion definitely needed a lot higher and you can just run it vertical until it meets the felt and bend it the angle of the roof running it up a bit and back down in a U shape & then drop to tank.
A bypass would have helped.

 

[ShaunCorbs]

Expansion definitely needed a lot higher and you can just run it vertical until it meets the felt and bend it the angle of the roof running it up a bit and back down in a U shape & then drop to tank.
A bypass would have helped.

its about 4' long as it is (from bend to tank) and thats the center so if i extend any more it would be going down to the other side (past pitch)

and bypass is the old gate valve that will be changed

but think you missed the point

turn heating on (doesnt pump over)
turn hot water on with heating still on (pumps over)
turn hot water off (stops pumping over)

 

[stevetheplumber]

is vent still teed off cylinder primary

 

[ShaunCorbs]

is vent still teed off cylinder primary

yes (they dont have separate vent) if thats what your on about on the heating sides

goes

vent - pump - bypass - heating port - hot water port

 

[kay-jay]

That's your problem then. The pipe Configuration is for gravity primaries not fully pumped. Alter the vent connection point

 

[ShaunCorbs]

That's your problem then. The pipe Configuration is for gravity primaries not fully pumped. Alter the vent connection point

where would you put it? as its tight and got one shot (combine vent and feed) ?