Gravity hot water to fully pumped / sealed

[eagleeye]

One of our installers currently fitted a new heat only boiler to replace an old floor standing with gravity hot water. At the time he never fitted any valves or cylinder stat etc so I have been called back there to basically start again. Been there today to do it and found that he had the pump on the return. Anyway I drained system and made the necessary alterations to the pipework by the boiler and fitted a mid position valve and a wireless cylinder stat (as the run is impossible to get a cable between the two). So currently the feed from the F + E tank goes into the return of the cylinder and the vent on the flow. The boiler is in a tight cupboard low to the ground in an extension of the side of the house and the cylinder is on the 1st floor in the middle of the main part of the house so you can imagine how the pipework runs

 

[Stu-B]

Crikey that looks snug! The filter is gonna be a devil of a job to open up!

 

[eagleeye]

Crikey that looks snug! The filter is gonna be a devil of a job to open up!

Yeah very tight. The filter is tight but can be open now. I've attached a pic of what it looked like before. Our surveyor has really mucked up here to be honest. He should of quoted for a system boiler for a start.

 

[SJB060685]

So this is an open vented system and not sealed? Pump can go on return on a vented but the cold feed should be piped to down into return shortly after the pump outlet, the system would be under negative pressure though. To be honest that looked a mess beforehand

 

[eagleeye]

So this is an open vented system and not sealed? Pump can go on return on a vented but the cold feed should be piped to down into return shortly after the pump outlet, the system would be under negative pressure though. To be honest that looked a mess beforehand

yes, open vented at the moment. Problem is that I cant make any alterations to the feed & vent on the cylinder as its as tight as a .......... and there is no way i can get feed or vent down to pump / boiler position. Bloody nightmare of a job.

Do you think my idea will work ok ?

 

[Chuck]

Er, careful, this is a public forum... Might want to take it to the Plumbers' Arms?

 

[ShaunCorbs]

agree pump should be on the return as they tend to last longer due to lower temp

check valve on the feed from the f and e
and a 2 bar safety valve on the vent
expansion vessel

thats along as you have an okish head eg 3m+

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[eagleeye]

agree pump should be on the return as they tend to last longer due to lower temp

check valve on the feed from the f and e
and a 2 bar safety valve on the vent
expansion vessel

thats along as you have an okish head eg 3m+

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Pressure Relief / Single Check Valve - Order Gas and Plumbing Supplies online at BES.co.uk. Low Prices, Free Next Day Delivery Available, 15k Plus Products in stock P/N: 18794

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So are you saying still use the F + E tank to fill the system and fit a check valve to the feed, 2 bar PRV on the vent as well as an expansion vessel or am i doing away with the f + e and filling via mains water ?

Also gonna have to leave the pump on the flow now as ive already changed it all now. Will that matter ?

Only place I can get vessel in is either above the boiler on the ground floor or in the place of the f + e tank.

 

[SJB060685]

If you leave the vent as is then whenever HW is called for it will pump over, in time it will sludge up the system. Im assuming Shaun is suggesting seal the system and do away with f and e tank, which is what I would suggest. Preferably the expansion vessel will go on return where it’s not exposed to high temperatures, if the pump is on return the vessel should be close to suction inlet of pump to maintain a positive pressure through boiler and around the system, thus eliminating any air ingress.

 

[ShaunCorbs]

So are you saying still use the F + E tank to fill the system and fit a check valve to the feed, 2 bar PRV on the vent as well as an expansion vessel or am i doing away with the f + e and filling via mains water ?

Also gonna have to leave the pump on the flow now as ive already changed it all now. Will that matter ?

Only place I can get vessel in is either above the boiler on the ground floor or in the place of the f + e tank.

leave the f and e tank in so it will stay the same pressure

sealing could cause issues with leaking on joints etc if in a concrete floor