Max Kw boiler size for 3 port valve.

[billski]

Hello all,
perhaps some one can tell me..is there a maximum size of kw boiler that can be used with a 3 port valve? The system is a gravity fed, 2 pipe system system with a heat only boiler.
British Gas have said the 3 port valve needs replacing with 2 2 port valves as the a 3 port should not be used with a boiler of 18 kwts or more. Any thoughts most appreciated.
Thanks.

 

[ShaunCorbs]

horse poo there should be a pump on your system tho

 

[PriestyUK]

Hmmmm never heard of that before, you can get a 28mm 3 port valve, 28mm for a maximum of 18kW seems abit lame to be honest but hey every day is a school day BG always know best :38:

 

[billski]

Hmmmm never heard of that before, you can get a 28mm 3 port valve, 28mm for a maximum of 18kW seems abit lame to be honest but hey every day is a school day BG always know best :38:

The existing pipe work is 22 mm and I've been asked to quote to replace the boiler. Honeywell say a 3 port can be used up to 26kwts so not sure what B gas are on about then. I've seen part of their quote and it says anything over 18kwts should be converted to 2 2 ports. Never heard that before so didn't know what to say.

 

[mfgs]

I thought the 22mm valve could only pass about 18kw of heat and the 28mm about 26kw? I could be wrong, but I seem to remember something like that. Converting to an S plan would be better anyway.

 

[ShaunCorbs]

I thought the 22mm valve could only pass about 18kw of heat and the 28mm about 26kw? I could be wrong, but I seem to remember something like that. Converting to an S plan would be better anyway.

22mm will handle 30 kw maximum so will handle most events

and agree s plans are better

 

[mfgs]

22mm will handle 30 kw maximum so will handle most events

and agree s plans are better

22mm 3 port definitely wont pass 30kw. I think its about 18kw or maybe 20, not more than that. That will also be split when the valve is in the mid position as well.

 

[leesparkykent]

From Honeywell The V4073A valve has been designed to control the flow of water in a small bore domestic central heating system where both radiator and hot water cylinder circulation are pumped. It is typically suited for systems up to 90,000 Btu/h (26 KW).

 

[ShaunCorbs]

22mm 3 port definitely wont pass 30kw. I think its about 18kw or maybe 20, not more than that. That will also be split when the valve is in the mid position as well.

honeywell and drayton are rated to just shy of 100,000 btu round about 28kw

 

[mfgs]

From Honeywell The V4073A valve has been designed to control the flow of water in a small bore domestic central heating system where both radiator and hot water cylinder circulation are pumped. It is typically suited for systems up to 90,000 Btu/h (26 KW).

Pretty sure that's for the 28mm valve, not the 22mm one.

 

[leesparkykent]

Pretty sure that's for the 28mm valve, not the 22mm one.

I'm just a sparky no plumber but is the bore of the valve the same size as the replacement ball you can buy is of the same size?

 

[ShaunCorbs]

Pretty sure that's for the 28mm valve, not the 22mm one.

as above same port size