Worcester system boiler on 1 pipe system

[so-solar]

Customer has contacted me to quote for ripping out open vent system and boiler and replace with 18i worcester and a megaflo, The only issue is she wants me to keep the 1 pipe system that is already installed as she has just revamped the whole house, the system has 10 rads and is still up and running!

Where do i stand with current regulations on this matter?

Has anybody pressurised a 1 pipe system in this way?

 

[Mike Jackson]

Used to do it a lot with warmfront jobs. They worked but obviously not as efficient as converting it to 2 pipe.

 

[so-solar]

I have been told it voids worcester warranty?

 

[R1CKY]

I was on an OFTEC course with Worcester recently and they mentioned that their oil boilers didn't like one pipe systems as the return temperature was too low and damages the main heat exchangers. Not sure if it is the same with gas, but perhaps the reason Worcester won't honour the warranty.

 

[plumber0808]

Phone worcester and ask them, I haven't heard that. Would be a bit strange as there are still quite a few 1 pipe systems about.
it will work but as said is less efficient.
If it is the case that worcester say no you could fit a intergas.

 

[Leo21]

A one pipe system return would be hotter not cooler surely?

 

[GasmanxxxR1]

It will work, the boiler will cycle more so it maybe worth fitting a lower rated kw boiler so it stays on longer

 

[vern]

A one pipe system return would be hotter not cooler surely?

Correct, hence why you cannot get delta t 20 degs, waste of time rip it out and start again!

 

[Mike Jackson]

So which bit of the first post didn't you understand? The customer doesn't want the disruption of ripping it all out. A modern boiler will work on a one pipe system, it will be more efficient than an old boiler but not work as well as one on a two pipe system.

 

[Kev the gas]

My main concern would be how well the system can be cleaned, Im sure that is Worcesters main concern.

I suggest all the rads off the wall to clean after using chemicals in the system for a few days.

Cantvreally see why the return temps would bother the boiler heat exchanger, does anybody actually achieve 20 degrees diff when doing any boiler exchange ?

 

[Kev the gas]

Should have also mentioned I do chuckle, sometimes even a little wee! When reading some of the benchmark documents when servicing boilers, amazing how accurate some installations are compared to the data badge.

Just wish they looked at the condense pipe requirements/ flue / gas supply requirements as well!

 

[Mike Jackson]

It's amazing how a year after the installation the inlet pressure at the boiler can drop to 15 mbar from the 20 stated on the benchmark document.

 

[Mike Jackson]

A guy I worked with on a couple of occasions used to fill in the benchmark before he started to save forgetting at the end.