Converting gravity hw to fully pumped....question?

[bigcheese]

I am 1 day into a 2 day job which includes changing radiator valves and a few other things, but mainly I am converting a gravity water pumped heating system to fully pumped.

This is what I have done so far. The boiler is floor standing in the kitchen with 28mm gravity circs going up to coil in cylinder. Heating circs are inaccessible at the back of the boiler. The pump is currently in the front of the boiler. I am utilising the gravity circs and changin it to a Y plan. Flow from boiler into airing cupboard - air seperator - pump - bypass - 3 port valve into coil and existing heating pipes.

My question is as follows :-

I would normally cap the old heating circs at the back of the boiler, but I can't get to these at all. They disappear into the floor. I have tried to pick them up upstairs to no avail. Only place they could come up is in a bedroom with expensive wooden floor, and customer has said this is a no go. Instead of capping them at the back of the boiler, would the system still work if I capped them off where the pump is in the front of the boiler?

Many thanks for reading this, and I apologise for rambling.

Any advice would be most welcome

 

[justlead1]

Hi, A lot of assumption, but if the system is feeding rads on both ground and first floor, its most likely that the pipe sizing has been designed from the existing boiler position. Stabbing into the first floor heating circuit may well effect the performance of the heating system. Good Luck

 

[John The Rad]

Why change it to a Y plan.
Why not just put a second pump on the 28mm circs near the HW cylinder, but first reduce the pipe to 22mm.
Leave the original pump on the CH.

 

[Hugh]

would a boiler inter-link work? a 2 channel time clock ect so that when hot water is selected the boiler heats, pump stays off and hw stills heats by gravity? just curious is it an oil boiler?

 

[david williams]

why a by pass on a y plan

 

[doitmyself]

Why not just put a second pump on the 28mm circs near the HW cylinder, but first reduce the pipe to 22mm.
Leave the original pump on the CH.

I agree. This is equivalent to the Grundfos Pumpplan - two pumps feed from a common source. Each pump acts as its own zone valve. Just make sure the hot water pump is set to the lowest speed and there is a balancing valve on the hot water circuit - otherwise it will grab all the circulation.

 

[colin324]

would a boiler inter-link work? a 2 channel time clock ect so that when hot water is selected the boiler heats, pump stays off and hw stills heats by gravity? just curious is it an oil boiler?

Yes you can. I have done this to my Gas boiler setup, with gravity hot water and pumped heating. Using the time clock outputs for CH and DW, I have connected a cylinder stat to the DW output, which then controls power to the hot water components, and the room stat is connected to the CH output to control the heating components.

Colin

 

[Blackcatgas]

Yes you can. I have done this to my Gas boiler setup, with gravity hot water and pumped heating. Using the time clock outputs for CH and DW, I have connected a cylinder stat to the DW output, which then controls power to the hot water components, and the room stat is connected to the CH output to control the heating components.

Colin

But surely when you put "just" the heating on the hot water gets heated still by gravity?.

 

[colin324]

You still get a small amount of heat input, but not too much. If you want none at all, it would be possible to fit a control valve on the inlet side to stop it.