Boiler headache.

[emscott]

I am having an extension built to include an ensuite bedroom/ bathroom.

My existing old style boiler is 27 years old but very reliable. When it was serviced last November the the plumber said he could still get all the parts for it. He said there's only 3 things ever to replace - thermocouple, valve (repaced 18 mths ago) and something else I cant remember - jets perhaps?

I still have my old copper cylinder, which has a feed off for a power shower in the existing bathroom.
My dilemma is whether or not I should replace this boiler with one of the new condensing ones which I have heard so many horror stories about.

If I do replace, wont my cylinder become redundant and require modifications to the power shower?

How long will a condensing boiler last? The shower in the new ensuite will be an electric shower so wont put any extra demand on the boiler, and I think the boiler will cope with the 2/3 new radiators in the new bathroom/bedroom. I have been told a condensing boiler will save on gas, but my heating bills are not unbearable and I think the capital outlay may not be justified (especially combined with the existing cylinder issue)

Any advice greatly appreciated.

 

[MarkBarl]

Don't confuse condensing with combination.
Condensing = The way it works. Combination = What it does.
A condensing boiler is one that passes the water circuit though the flue gas to save energy by pre heating the water before it passes through the main heat exchanger i.e. the burner will not have to work as hard to heat the water to the temperature required. Also known as High Efficacy (HE).
A combination boiler is a type of boiler that "combines" heating and also heats hot water on demand rather than storing it in a cylinder. You would want a standard Condensing boiler.

That said I am sure that the learned fellows on this forum will be able to come up with all the technical details to be able to work out if your existing boiler is capable of what you want it to do. I would suggest though that you post the current Make, Model, No. of existing radiators and any other details of your current system that you have to hand.

 

[mikej2005]

If I do replace, wont my cylinder become redundant and require modifications to the power shower?

Your cylinder will only become redundant if you go for a condensing combi and I don't think you'll be able to use your existing power shower with a combi anyway.

The alternatives are a condensing conventional (gravity-fed) or system (pressurised) boiler and either keep your existing cylinder or replace with an unvented (pressurised) equivalent.

 

[Space cat]

The proper way to do this is to add up your heat losses, including the new extension, and compare them with the heat output of your boiler. There's an easier way but it's not exactly reliable.

Think back to the last spell of really cold weather. If you can remember that far back, was the boiler running flat out to keep the house warm or was it cycling on and off as usual. If it was running flat out and you add extra radiators it will not be up to the job next time.

I would leave the old boiler alone to start with and add those radiators. It'll probably work.

 

[Symptoms]

Good advise from Space Cat. Cost effective option is to fit the new rads (you'd have to do this either way) on the 'old' system & see if it works. If it struggles lay-out on the cost of a new boiler. If it ain't bust, etc, etc.

 

[emscott]

Thanks for your advise - I am very much in agreement with the 'if it aint broke dont fix it' school of thought.

The boiler is an Ideal E type RS Balanced Flue 80 N and looks like a bit of a dinosaur - but seems to work well.

I cant ever recall it having to work flat out. The house is well insulated and is south facing and seems to retain a lot of day time sun warmth, too much so in summer!

I have 12 radiators at the moment, a couple of which are long double radiators. As you say, I will try it and see. If it begins to struggle I will have to take the plunge.

Thanks again for your expertise - and putting me straight on condensing and combination. The older I get, the more I get to realise how much I dont know!

 

[emscott]

Oh yes, meant to give the output/input details.

Input 104,000, Output 80,000

Then it has some other figures that says input 78,000, output 60,000

I,m guessing that means its only 77% efficient (80/104)?

 

[mikej2005]

I,m guessing that means its only 77% efficient (80/104)?

If it's 27 years old, then it'll probably be even less efficient than that I would have thought.

 

[gas4you]

I would think that if you said it was 60% efficient I think that would be over generous

 

[emscott]

That sound quite alarming! I,m paying about £600 per year to heat it. On those figures I could be saving, say, a good £200/£250 per year?

Its a 4 bedroom detached. I was quite happy with £600 per year. Now I,m starting to hope the boiler packs up sooner rather than later!

Still, I dont want to fork out for a new boiler and labour unless its really required.

 

[gas4you]

If your HW is gravity heated and you only have a room stat and not trv's on each rad, then by changing your boiler to a new condensing one, updating to the latest controls, fitting trv's, changing your HW cylinder to a new fast recovery type and seeing that a new system will be fully pumped, you would be looking to save approx 1/3rd off your annual heating bill.