Boiler for single pipe system

[KevinJohn]

I am considering replacing my 8 year old gas-fired back boiler with a new gas condensing one. I have on old but perfectly good single pipe central heating system. The BG man said that a new boiler would not operate properly on a single pipe system and the whole thing would have to be replaced. I can't believe that technology has regressed so that a modern boiler cannot operate on an old system. Any thoughts

[tom squires]

Hi
The single pipe system is a very inefficient system which allows the first radiator to be very hot, while the last in the system, having mixed with a great deal of cool water, is usually cold
where as in a 2 pipe system two separate pipes go to each radiator, one feeding the radiator (flow), and one taking water back to the boiler (return). Much more efficient than the single pipe system as this system can be balanced properly.
so it would cost more to install but you will notice a big difference in efficency

[adgediy]

I only just discovered this forum - sorry for the late post.

I have had a single-pipe system that has 17 radiators/towel rails attached for the last 34 years. I keep hearing how dreadful they are and can only say that that is not my experience. Yes, it takes longer for the furthest out radiators to heat up, but not disasatrously so. I have also installed thermostatic valves on almost all of them, another no-no if you listen to the 'experts'.

The important thing is that the radiators all have 'swept T' connections to the single pipe. This allows the venturi effect to really work. Having said that, I have attached a couple of new rads by conventional T's, and they also work just fine.

I have heard before that modern condensing boilers don't work well with single-pipe systems. I can't understand why not, perhaps someone else knows? I have been contemplating replacing my 15-year old Gloworm boiler with something newer. Our service engineer says that the new condensing boilers are very complex and are much more failure-prone. If that's the case, and they also don't work well with a single-pipe system I'm staying with my present old but reliable boiler indefinitely. £2,00 for a new boiler and £x,000 to have my floors ripped up and a second pipe run put in doesn't seem like a good deal to me.

As a final note, a friend keeps meticulous records of gas consumption. He installed a condensing boiler a couple of years ago, but has not noticed any savings in gas consumption.

[heating-eng]

I only just discovered this forum - sorry for the late post.

I have had a single-pipe system that has 17 radiators/towel rails attached for the last 34 years. I keep hearing how dreadful they are and can only say that that is not my experience. Yes, it takes longer for the furthest out radiators to heat up, but not disasatrously so. I have also installed thermostatic valves on almost all of them, another no-no if you listen to the 'experts'.

The important thing is that the radiators all have 'swept T' connections to the single pipe. This allows the venturi effect to really work. Having said that, I have attached a couple of new rads by conventional T's, and they also work just fine.

I have heard before that modern condensing boilers don't work well with single-pipe systems. I can't understand why not, perhaps someone else knows? I have been contemplating replacing my 15-year old Gloworm boiler with something newer. Our service engineer says that the new condensing boilers are very complex and are much more failure-prone. If that's the case, and they also don't work well with a single-pipe system I'm staying with my present old but reliable boiler indefinitely. £2,00 for a new boiler and £x,000 to have my floors ripped up and a second pipe run put in doesn't seem like a good deal to me.

As a final note, a friend keeps meticulous records of gas consumption. He installed a condensing boiler a couple of years ago, but has not noticed any savings in gas consumption.

it is great to see that you know more than the experts .
when installing a new boiler you need to have 11 degrees temp differance on the flow and return to help make the system run to its best.
you wouldnt be able to do that on a 4 rad system let alone any bigger so the BG guy is correct .
i worked at BG for 20 years and also worked in system design so i will tell you that your one pipe system does not work well you just dont know any difference if you had a full new system it would all work much better.

i would also advise you fit one one of these filters http://www.magnaclean.org/