can a modern condensing boiler do a 1-pipe system?

[TerryWaite]

I have a customer who has a one pipe system in steel, 15-20 radiators on it, with an old floor mounted boiler. He wants to split the system up into two and put two combis in. I can do all the pipework side of things not a problem, just wondered though would a standard condensing combi do 8-9 large cast iron rads off a 1-pipe ring circuit? if i take 22mm to one end, jump up to 1 1/2" or whatever and then the same back to the boiler. I am an industrial heating engineer by trade but have never had a small boiler feeding large bore pipe like this.

cheers

John

 

[Roger Welton]

I believe worcester allow there boilers to be used on a one pipe system, though it is obviously not good practice.

I'd be concerned the old cast iron rads wouldn't be up to the job of taking the increased pressure of a sealed system. You would also have to be very carefull about calculating the system volume if there are long runs of large diameter pipework with respect to expansion vessel sizing.

 

[stevetheplumber]

at the end of the day the heat source is irrelevent provided you get hot water in and out of the cicuit it should work as it did previously
where you could have problems is getting any support from manufacturers in event of problems and possibly warranty claims o might be best to try and get some sort of dialouge with them at the planning stage
another solution could be plate heat exchangers to isolate boiler from system this would also help with the debris in an old system,
your probably going to need to come of the boilers in more than 22mm pipe if you want to use full capacity of the boiler as a rule anything over 50,000 btus needs 28mm
i cant see any problem with cast iron rads and preasure as one bar(14.5psi) isnt exactly high preasure many office blocks are over a 80ft head(40psi)

 

[AWheating]

one pipe is fine on a modern boiler, just a bugger to flush the system.

 

[SafeGasInstall]

John any chance to repipe ?

If not you have to speak to Manufactories to see what they say

 

[jtsplumbing]

Need to put a good filter on system with all that iron pipe etc new boilers not as forgiveing as the old ones (clog up easy)

 

[mfgs]

Worcester say you can fit their boilers on a one pipe system, I have fitted a few on one pipes now and never had a problem.

 

[phpaul]

I have a customer who has a one pipe system in steel, 15-20 radiators on it, with an old floor mounted boiler. He wants to split the system up into two and put two combis in. I can do all the pipework side of things not a problem, just wondered though would a standard condensing combi do 8-9 large cast iron rads off a 1-pipe ring circuit? if i take 22mm to one end, jump up to 1 1/2" or whatever and then the same back to the boiler. I am an industrial heating engineer by trade but have never had a small boiler feeding large bore pipe like this.

cheers

John

use a barrier system .. use a heat exchanger as a barrier between the ch rads and the boiler put both boilers together like in a commercial system
and use digital room stats that allow u to program each rad independently . for time and temp.

 

[TerryWaite]

Thanks very much, will bear all this in mind, and Stan, I would like to repipe but customer is very tight!