Can a boiler connect to CH/DHW anywhere on the "circuit"?

ijrwe

I won't be DIY'ing (or is that D'ingIM?) this job but I want to know the situation so that I can consider how big a job we're dealing with and approach contractors accordingly.

Basically, given a normal combi boiler, with outputs to DHW and CH, can it connect to any given point on those "circuits" or are there special requirements.

For instance, say I plan to have a boiler fitted on a certain patch of wall, and within arms length of that point is a radiator and pipe (CH circuit) and also a hot water pipe and tap (DHW circuit), can I assume that the boiler will happily plug in to those points and successfully feed the rest of the house with hot water?


Thanks,

diywhynot

ijrwe wrote: »

can I assume that the boiler will happily plug in to those points and successfully feed the rest of the house with hot water?
Thanks,

Maybe, maybe not...best answered by a RGI who has seen the job.

booty40uk

Hot and cold feeds should be ok. Flow and returns will need to tee into existing 22mm runs. All dead legs will need removing. Gas will need to be done by an rgi and may need resizing. Havnt seen job so cant say for sure.

malc_b

I dunno what the previous posters are thinking but the answer is NO. The CH feed out of the boiler will be 22mm pipe. That will then split off into 15mm sections feeding radiators (or micro-bore). It's a tree and branch structure and the return is the same. You can't feed the entire CH from on (15mm) branch. Likewise the HW will be 22mm feed to bath and then 15mm branches to taps. You can't feed the bath from a 15mm branch.

If you want to move a boiler you need to look at extending the 22mm pipework to the new location, or diverting the 22mm from some point to the new location.

ic

My bath and shower runs from a 15mm feed from the combi boiler. Isn't 22mm on the hot water a hangover of gravity fed systems?

booty40uk

Malc, if you read my post it says that the flow and return need to be teed into the 22mm. DHW from the combi will come out in 15mm and cold feed into it will be 15mm. Again, cut out any dead legs.

ijrwe

Right, I see - OK, the layout of CH/rads is not as I imagined. That makes sense, though.

It seems that, as noted above, the "convenient" gas supply in my kitchen is actually a useless 15mm pipe so a new run would have to be taken from the meter anyway, AND the 22mm CH pipes are miles away as well.

I will look into the possibility of installing the boiler in a bedroom (where the old water tanks are) as this area definitely has everything except gas, and if I'd need a new pipe for that anyway it could just go there without much trouble.