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Discussion in 'Central Heating Forum' started by ShaunCorbs, Jul 6, 2018.
Discuss Feed and Vent fun :DDDDD in the Central Heating Forum area at UKPlumbersForums.co.uk.
Not sure how to read that?
Does the gate valve stay open in normal operation?
I can't see how this differs from just having an expansion vessel, but with pre-charge pressure somewhat lower than normal.
Still need to put the expansion vessel connection in the right place, to avoid having negative pressure somewhere.
I converted mine about 20 years back. Old cast iron floorstanding boiler, gravity HW, pump next to boiler, pumping downwards. No controls. Cold feed to boiler return.
Scrapped the boiler and installed wall-mounted condensing. Moved the pump to the airing cupboard, added diverter valve (system W), open vent, cold feed and DV in the airing cupboard. Added cylinder and room stats. Re-used the gravity 28mm pipes as pump suction and cylinder return.
Still working OK.
Gate valve stays open. Ans yes you can just seal, add vessel and PRV and have virtually no pressure. Its just convenient using the existing header instead of a filling loop if its already there.
That is exactly what system I have to work on!
Cast iron oil boiler with 28mm gravities to cylinder and 28mm pumped (pump is also on return pipe) to rads. No controls.
The feed pipe joins in at tee at return at cylinder.
Your new pipe up arrangement would be nearly what I would ideally do, but difficult on this house. I might risk trying to seal the system - but at a low charge.
As to Vee’s point about sealing the system using gravity feed from f&e tank and non return valve, - I have came across systems done that way, some of which are fed from the cwt cold supply.
Personally I don’t like it because risk of contaminating cwt, also disadvantage that the sealed system will keep being topped up in an event of a bad leak, like nail through a pipe. Although constant top up has also advantages.
In my case the F/E tank is almost directly above the airing cupboard, so open vent and cold fill no problem. I chased the wall in the hall for the roomstat, and it was fiddly getting the lead through to the airing cupboard. Eberle roomstat, because it was cheap, but no complaints, has anticipator heater and gives excellent control. I guess you'll use a radio-controlled roomstat so won't have the cabling problem.
There is a common heating flow pipe not far from the airing cupboard so I ran a pipe under the floorboards and tee'd into that with CH flow from the DV.
My very scientific experiment
34" of head
1" single check valve
1 Williams f and e tank
It works brilliant
Sorry Shaun, you've lost me. What works brilliant?
Didn't think there was going to be enough head to open the check valve
That's looks like low-head check valve. Am I right?
With the suggested scheme the valve needs to close to prevent upward flow, if I understand correctly. Does it have a spring-loaded flap? Unlikely it will close otherwise. Or maybe use 2 90° bends so the valve is in a horizontal section, if it's the right type of valve. Or maybe 2 return bends so it's vertically down, but that gets a bit messy.
dont have a clue, bought the check valve on the designed i liked the most
yes its spring loaded in the closed position
OK, looks like you have about 1.2m opening the valve on your rig. There should be more than that when installed.
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