Boiler dead, do I need a whole new system?

[cupsandtrousers]

Hi,

I have an old Ideal Mexico RS 40/60 running on a single pipe system and both the heat exchanger and burner have had it. I've had loads of opposing views from different local plumbers and even BG about whether we can put a new boiler on the system or have to run a new two pipe system through the whole house.

BG and a few of the locals think a Mexico HE would work fine but most of the independents I've spoken to say it would be against building regs as can't fit effective thermostats to single pipe.

I've tried getting the parts I need to repair the boiler for months now as that would be the easiest option but just can't find the burner.

Can anyone tell me definitively: Is it possible to put a new boiler onto a single pipe system without upgrading it? And is there anyone here in the South-West who fancies coming to have a look at it?

PS - even better would be anyone who has an old RS40/60 burner lying around they want to get rid of!!

Thanks.

 

[mickyg]

Its a tricky one really. If the one pipe system has been well installed and balanced then yes there's no reason why a new condensing boiler shouldn't work, however many 1 pipe systems I encounter are poorly laid out and often parts of the system have never worked particularly well from day one. As far as choosing a boiler is concerned it really makes no odds which one you go for whether it be a Mexico or anything else. Personally I wouldn't touch a Mexico HE with a large pole, asfaik its just an Icos in disguise. Google that name and you'll end up having nightmares.
Probably best you find a good competent heating engineer to have a look over the system and give some decent advise. In my experience engineers who also do commercial sometimes tend to have a better understanding of 1 pipe systems and achieving suitable flow rates for condensing boilers as its more common place in commercial.

 

[D_Hailsham]

BG and a few of the locals think a Mexico HE would work fine but most of the independents I've spoken to say it would be against building regs as can't fit effective thermostats to single pipe.

I can't comment on the single/twin pipe debate, but I can say that there is no obligation to fit TRVs if all you are doing is replacing the boiler. It's complicated, so bear with me.

The Domestic Heating Compliance Guide (which is the relevant document) divides work into two categories: new systems and replacement systems. In general a replacement system has to comply with the same criteria as a new system, but there are exceptions.

The first criteria is the number of zones: For new installations, if the floor area is less than 150m² there has to be two zones with independent temperature control: the main living area and the rest of the house. If the area is over 150m2 there must be two zones with separate time and temperature controls.

If it is a replacement system, and only the boiler is being replaced, you can have just one zone.

Now some might argue that this only apples to properties over 150m², but it does not say that.

The second criteria is temperature control. This says, for both new and replacement systems:

Separate temperature control of zones within the dwelling shall be provided using:
i. Room themostats or programmable thermostats in all zones; OR
ii. A room thermostat or programmable thermostat in the main zone, and individual radiator controls such as TRVs on all rads in the other zones; OR
iii. a combination of (i) and (ii) above.

Combining both criteria you can see that if you replace just the boiler, you must have a room thermostat - criteria (i) - but there is no obligation to fit TRVs.

 

[gas4you]

I just completed exactly the same type of job yesterday.

Old mexico on a single pipe system, rads as old as they come and needed to be left for 'character'. All new wooden floors laid, so no chance or replacing pipe work and rads.

Changed it to a fully pumped & controlled system with a new condensing system boiler.

Everything works fine. Didn't fit any extra trv's, as D Hailsham points out, no legal requirement to do so.

Apparently I got the job, not on price, but because I was the only one willing to take it on without replacing everything.

 

[boabcelt]

Danfoss do a full flow TRV which is suitable for single pipe systems. We just fitted 50 odd of them in a university building, along with 3 Hamworthy variheat condensing boilers.

 

[PEDANTICVINDICTIVEMAN]

First off it's your money, second does the heating work ok at the moment, if so I would say as long as you flush and inhibit it should work ok with a new boiler, it may not condense and work as efficient as on a two pipe though.

Why not fit the boiler ect as is, then if it doesnt' work "then" renew pipework.

I fitted a Worcester28Cdi on a one pipe system years ago, BG said it wouldn't work, it worked absolutaly fine and still is.