Megaflo Install Questioj

[3george]

My first post so go easy on me please. I'm not a plumber or heating engineer just a layman trying to understand what I'm being told by various tradesmen.

I'm considering having an unvented Megaflo installed to replace an aging Gledhill thermal store. The Megaflo is the 250L indirect model. My question is regarding the discharge pipework.

There is an existing pipe which vents to an outside wall which I intend to use for the Megaflo discharge ( which will be bought down to ground level with a cage around it etc. ) The currently vented primary circuit to the Megaflo will be sealed up and made unvented and I understand an expansion vessel and discharge pipe will be required.

My question simply put - do I need a separate ( and second ) discharge pipe for the primary circuit or can this use the one for the Megaflow.

I've explained this as best as I can and I hope this makes sense - if you need more information please let me know.

Thanks - 3george.

 

[sooey]

The hot water in the cylinder needs a discharge pipe, and the hot water in the seperate primary circuit also needs a discharge pipe. The megaflo discharge pipework is very important and needs to be sized according to it's length. The installer will sort that out, but your present discharge pipe will probably not be suitable.

 

[3george]

Sooey,

Thanks for the prompt reply, I'm aware both the cylinder and primary circuit need a discharge pipe.

The existing discharge is 22mm copper to an outside wall at landing height.

I've read the discharge pipe sizing requirements in the Megaflo installation booklet. When the Megaflo is installed there would be at least a 1m drop from the PRV and tundish before it turns 90 degrees twice to get to an outside wall which is less than 4m away.

If I've read the sizing guidelines correctly then this existing pipework is within spec for the cylinder discharge, but my question was can it also cope with any potential primary circuit discharge as well ?

Thanks - 3george.

 

[sooey]

With regard to the length, as you'll have read, if it's over 9 mtrs effective length it will need to be in 28mm, yours would be over that if "landing height" means upstairs. I don't see why the primary circuit blow off couldn't utilise the same pipe though, I've never done it like that myself but someone will put us straight if there's a reason why it shouldn't be done.

 

[gas4you]

I've used one discharge pipe for both megaflo and primary heating. Just size for megaflo. This is what needs G3 compliance.

 

[DP]

Do not forget to submit installation details to BC.