Condensing Gas Boilers

[FB.]

Building Regs Part L1 again via Mr Prescott.

First your system. Boilers used to be fitted using gravity hot water and pumped central heating. Easy to identify the boiler will have 4 water pipes leading away from it. 2 to the hot water cylinder and 2 to the central heating system. If your system is like this you will need a complete repipe to a fully pumped system (only 2 water pipes coming from the boiler.)

Just double-checked and the boiler has only two pipes coming from it.

It's a very-late-1980's or very-early-1990's-model Potterton Profile 60e, fitted when the house was built around 1989-91.

[Potstubsdustbins]

F.B. Luvely jubbly your half way there. Yours is a fully pumped system with an electro/mechanical 3 port valve. If you haven't got a room stat and cylinder stat they can easily be wired into whats existing. The valve and programmer you already have are the two most expensive bits of the control system.

You probably have a Profile or Prima, cast iron heat exchanger, boiler thermostat, gas valve and thermocouple. Not much to go wrong there.

On modern boilers the need for extra efficiency has lead to the developement of low water content heat exchangers made of thin stailess steel (in the best boilers). This has to be protected by overheat stats and various other gizmos. Fans now have to be able to run at varying speeds through the demand cycle an other set of things to go wrong.

The gas air mixture is now premixed in other words the fan blows air into the gas way before burning where as before it used to pull the products of combustion out of the boiler. And all this is on a system boiler a combi gets much worse with flow switches etc, etc.

Boiler service life is now down to about 10 years and according to Which magazine you can expect to spend £1000 on repairs during that time.

Replace a good old reliable Potterton with the same, if I could I would not be buying lottery tickets.

Keep the old girl going as long as poss, I have just checked and if it is a Prima/Profile all spares are still available.

Colin

[Potstubsdustbins]

Well bu**er me I guessed right a good old Profile.

Off for my dram now catch you all on the morrow

Colin

[FB.]

You probably have a Profile or Prima, cast iron heat exchanger, boiler thermostat, gas valve and thermocouple. Not much to go wrong there.

Good guess. I'm impressed.
The reason I wasn't specific is that I didn't expect to find someone such as yourself (I looked at your profile a little while ago and see that this kind of thing is how you earn a living).
I'll know where to come when the old girl finally pops her clogs and I'll dig out this topic - it might even have got you a job one day in the future.

Thanks for your help - it's appreciated. If any other thoughts cross your mind in coming days, I'd be interested in them.

Cheers,
F

[FB.]

If you haven't got a room stat and cylinder stat they can easily be wired into whats existing.

The hot water tank has a small grey coin-adjusted thermostat box (about two inches square and protrudes about half-inch from the side) - Honeywell, with adjustment from about 45'C to 65'C, which is wired-in to the gas boiler timer in the airing cupboard.

The dining room wall has a grey box, about three inches in size in all directions - Honeywell thermostat - with a temperature-marked dial for controlling the room temperature, from 10'C to 30'C.

Are those what you're referring to?


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[FB.]

Boiler service life is now down to about 10 years and according to Which magazine you can expect to spend £1000 on repairs during that time.

So running some numbers based on the following assumptions:

Cost of new boiler installation: £2500
Cost of repairs over ten years: £1000
Annual cost for a service after year-5 (post-5yr-warranty): £100x5yrs = £500
Total cost over ten years: £4000 = £400 per year just to own the boiler.
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Then the cost of gas (and some electricity to run the pumps, fans and electronics).
Our annual gas usage is likely to be about 14000kWh with a 65% efficient boiler (therefore actual heat delivered to the house after exhaust losses is 9100kWh per year).
Assuming we can get a new condenser boiler to run at 87% efficiency with our older pipes etc, it would drop our gas usage to 10500kWh per year, for a cost of about £550.
Likely cost of electricity to run the pumps, fans and electronics of a boiler: £50
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Total annual cost over ten years, to own, service and fuel the boiler: £1000
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Total annual cost of switching to using 9100kWh of electricity (100% efficient) in place of gas: £1050

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[chris]

Erk, misread the title - sorry

lack of sleep!

[chris]

Oh, was going to say that Ideal have some new model out, which is supposed to be amazing and all this... considering their track record, we opted for the Worcester.. the Ideal (Logic + I think it's called) had more throughput or something, and a 7yr guarantee, and all singing and dancing things as they're trying to make a come back - but as Colin said.. I didn't want to be a guinea pig for a new boiler. Yes, it has great reviews and the warranty which supposedly is excellent to back it up, but spending over £2k on something - and being the tight so and so that I am I wanted to ensure it was money well spent

[veggiechicken]

So running some numbers based on the following assumptions:

Cost of new boiler installation: £2500
Cost of repairs over ten years: £1000
Annual cost for a service after year-5 (post-5yr-warranty): £100x5yrs = £500
Total cost over ten years: £4000 = £400 per year just to own the boiler.
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Doesn't the boiler need servicing annually even while its under warranty?
I have a maintenance contract with a local firm who installed the boiler. I pay about £14 a month and that covers the annual service, emergency callout and all parts and labour. Better still, they live locally and they're always available.

[FB.]

Doesn't the boiler need servicing annually even while its under warranty?

I don't know, to be honest.
I thought a new boiler might be like a new car shouldn't need (and doesn't have to have) an MoT for the first few years.
Or maybe - like a car - a little light comes on after a set amount of usage or timespan, to say that it's in need of a service.
But if the boiler is opened for servicing, would the warranty be immediately void?

[veggiechicken]

I expect Potty will be along later to explain it, FB

[Potstubsdustbins]

With every new boiler you gets a 'Benchmark' booklet, This records who installed and commissioned the boiler and also is the service record. It will need to be at least checked every year and the record completed for the guarantee to remain in place.

If you use a truely competent honest gas engineer,the cost for the first few years should be negligible.

I use a flue gas analyzer to see how the boiler is performing before starting work. The ratio of CO, C02 and O2 triggers a service at a high point of .004. Today I attended a boiler fitted a year ago and the reading was still .0006. I usually find that unless there is a problem we don't strip and clean a modern boiler for 3 to 4 years and so for private customers as opposed to landlords there is very little expense about £25.

As to costings, £100 for a service I should be so lucky. For a full landlords gas safety inspection including 1 boiler and all the others necessary checks the going rate around here is £70-50p. This includes all the legal paperwork.

F.B. as to your little boxes, yes they are the thermostats, providing they are all in working condition you have a 'nap hand'. No repipe or control system needed.

Colin.

[Potstubsdustbins]

Seeing your talking about £2500 for your boiler swap I have done some investigations.


If all is as you have said with regards to the control system, the flue termination meets criteria and there is a waste pipe or drain in the locale its a doddle of a job, my man would be in and out in a day.

You really should be looking at some where around £1500 including TRV's if you need them.

Colin

[FB.]

If all is as you have said with regards to the control system, the flue termination meets criteria and there is a waste pipe or drain in the locale its a doddle of a job, my man would be in and out in a day.

I think there would be a problem with the draining away of condensation and I would expect some kind of special work to be required.
The boiler lives in an understairs cupboard, accessed via the kitchen. However, running a drainage pipe would have to get past a doorway.

Also, living near Cambridge means that everything is very expensive. Houses and rents here aren't much less than in London - with a consequent effect on business' costs.

Floor plan attached:

[Potstubsdustbins]

Looks like there may be a further cupboard under the stairs off the hall, if so it may well be possible to run the condensate to the basin waste.

If not you can use a soakaway out side a little more cost but not much.

Colin