tricky pipe work

[moliver34]

Can any one help!

i've currently got a pumped cental heating system with a gravity hot supply to the hot water cylinder. The boiler is oil fired, with a pump inside the casing.

How can I convert the pipe work, so it is a fully pumped system.

At present there are four pipes coming from the boiler. Two are the flow and return from the central heating, the other two go to the hot water cylinder. There are no valves on the system, no cylinder thermostat or room thermostat!!

There is a feed pipe from the feed and expansion tank in the loft and a vent pipe to it.

any help would be appreciated

 

[gas4you]

Quite a standard job to come across these days.

Basically 4 options all ending in the same result.

1) re-pipe from boiler to airing cupboard with 2 new flow and return pipes and fit a control pack and new pump.

2) disconnect heating flow & returns and plug at boiler. Use existing 28mm gravity pipes as flow and return to airing cupboard, fit new contol pack and adjust siting/installation for the vent and cold feed. Find existing 22mm heating pipes under floor upstairs

3) same as 2 really but use 22mm pipes from boiler and plug 28mm primaries.

4) fit a twin pump system, pump the hot water primaries and pump the heating. Grundfos do a purpose made twin pump for just this and then fit a new twin pump control pack.

Only you can decide which is easiest as you're on site. Usually I would go for 1 or 2 in that order and flush out system upon completion.

 

[moliver34]

Thank you dave.

I posted the same 'question' on another site, similar to this one...and got abuse!!

Your help will save me alot of hassle.

Thank you again

 

[corgiman]

Thank you dave.

I posted the same 'question' on another site, similar to this one...and got abuse!!

Your help will save me alot of hassle.

Thank you again

other sites are not as freindly as ours

we are the fluffy bunnies of plumbing

 

[moliver34]

I guessed that Corgiman!

The "other site" deals mainly with Oil boiler installs..can can you guess who they are?

 

[oilman]

Ha! if you want abuse this is the place to come to. Wait till Softus gets on your case........

just a warning about the twin pump, they have two circular plastic non return valves in, and things go really screwey when one doesn't quite seat properly. Then you need to have some spares with you, otherwise Plumb Center want you to buy a minimum order quantity when it becomes cheaper to buy a new pump. All for the sake of two 17p valves. Hint: Warmflow combi uses a twin pump

 

[wilhelm]

........thats if youve got a spare 3 hours to wade through endless pages of quotes...........

thudddddddd.



unquote.

 

[bripl]

oilman wrote
Warmflow combi uses a twin pump
no problems with the ones i have fitted work a treat and kill gas boilers with its performance 18l a min,only downside with these boilers is the lack of controls

 

[oilman]

There aren't any problems till the problems arise, when you have the radiators heating all the time. I suggest you carry some very low cost valves to save the grief I had on a Friday with no valves, and even Grundfos baulked at sending a couple..............

 

[bripl]

been fitting them for a couple of years and had no bother YET,where are they available from in case i come across this prob,thanks oilman

 

[dal5band]

I've got a gas boiler with two pumps - the boiler and CH pump are modern ones about 4 years old.
However, the HW pump is an SMC cadet, 1975 vintage - still working.

 

[ChrisR]

There is another way:
just put a second pump in, in the gravity return to the boiler from the HW cyl.
Add stats to switch it on when the cylinder is demanding heat AND the pipe's hot.

If the boiler's set high you still get a little gravity heating , but with the pump in the way, not much. You could of course add a zone valve in the return to stop it.
The point about using the return is that you leave the flow open, which you need to if it as usual, goes on up to be the vent.