Replacement Boiler

[yatm57]

We have an old Ideal E floor standing boiler, probably 20+ years old. This winter the radiators on the extreme ends have gone cold. There is no sludge that is worth a mention. The pump could be on the last legs.

Given the age of the boiler, I thought it may be best to go for replacement as the new boilers are supposed to be far more efficient. Do you agree? The house is occupied during the day and the boiler runs most of the time. Hence, I felt, we could save quite a bit on gas.
We have traditional, radiators and cylinder arrangement and like to keep it that way. I felt we need about 25-30 KW (5 beds, bath, shower, washing, etc). Any suggestions? Any views on Open and Sealed systems? I tried to research the subject and ended up with more questions!

Any advice would be much appreciated.

 

[frank uk]

How many rads have you got?.If you wanted it done without expense being more than need be,go for a swap maybe a ideal mexico or potterton kingfisher ,which can come with f/flue option.I would look at both option's,a combi,you would need a large 30 k boiler,and you can site it virtually anywere you want,just get a good firm in who wont cut corners i.e no 22mm gas supply from metre or dont clean old rads and pipework correctly

 

[D_Hailsham]

We have traditional, radiators and cylinder arrangement and like to keep it that way. I felt we need about 25-30 KW (5 beds, bath, shower, washing, etc).

Your old boiler will be very inefficient, say 65-70%, so you will certainly save fuel with a condensing one. If you want a ball park figure for the size boiler you need, go to Sedbuk and run their "Recommended Boiler Size" calculator. This is worked on the volume and construction of the whole house, but is reasonably accurate compared to detailed room by room calculators.

You may be surprised how small a boiler you actually need. Many systems were over-specified in the past - and still are by "heating engineers" who use rule-of thumb methods for estimating the requirements!

The other thing is that, if your existing system has been over-specified and the rads are larger than actually required, you will be able to run your new condensing boiler at a lower temperature and save even more fuel.

As you have all the pipework etc in place, I would not even think about installing a combi in a 5 bed house

 

[gas4you]

I would have thought that a 24Kw boiler would easily cope, possibly even an 18Kw with proper calculations and seperate timed HW.

A system boiler is always going to be better as a sealed system will (should) outlast an open vent system if fitted correctly, as the water will not be constantly aerated.

The downside is that increased pressure in your system may find a few weak spots and coupled with a good powerflush, may cause a leak, very unlikely however, but must be considered.

If your hw cylinder is also this age then I wouldrecommend upgrading this to a new fast recovery model and whilst at it upgrade all the controls, changing to fully pumped, as I assume with a boiler this age it will be gravity primary which is no longer allowed under current regs when you change your boiler.

 

[bengasman]

Do not spec your own boiler and tell the heating engineer to fit that size. I guess you can do with half of what you think.
I have yet to find the first open system of that age that is not full of carp unless it has been cleaned in the recent past. As boilers work or don’t work in general, the cold rads indicate either blockage or dying pump, but the boiler could be perfectly okay.
Yes you can easily cut a third of your gasbill, but how long will it take you to recoup the 3 grand a good job will cost you?
As it is very likely you will need a new cylinder and controls, it would be more economical to install a combi, cheaper to run as well, which is easily doable with one bath and one shower.

 

[yatm57]

Thanks for all the helpful comments.

I have tried the boiler sizer as suggested. That tells me that about 25KW would do. We have hardwood flooring for most of ground floor. Hence, I am a bit apprehensive about a sealed system, in case there are problems under floor. I guess the real weak point would be radiator connections. Powerflush may highlight the weak points?

I am not going to spec the boiler, but, wanted to have a good idea about the available options to make informed decision. I also wanted to look for some of the more reliable boilers. Any help in this area would also be helpful. Local Plumbase suggested Viessmann, I have never heard of the make.

Because of the shape of the house it has lots of small radiators. 15 Rads and 2 towel rails! I don't really want to go for a combi. We have a pumped shower for example. The cylinder has a new thermostat and we have a newish room stat and timer.

I looked at the various options and found Conventional boilers and System boilers. Can someone explain the difference please?

Thanks.

 

[gas4you]

Conventional boilers use a fedd and expansion tank in the loft.

Sealed system boilers are as it says on the tin, sealed and pressurised, with an internal expansion vessel, most usually incorporate a pump as well.

This type may be physically larger but the system will last longer.

Viessmann very good, but after sales can be bit iffy.

Vaillant much the same, depending where you are.

WB good also.

If you buy the best boiler and have an idiot fit it then it will fail quicker than a B & Q special fitted by someone competent.

 

[frank uk]

I would advise you to just have a look at keston boiler's.I have only installed 5 of these but they are amazing boiler's.I fitted one last month in a church that had 14 big rads,10 were large double's,and i fitted new cylinder ,this was a pressurised system,so it needed a ex vessel and i was told by two other firm's who had priced the job,that the boiler was to small and they needed a conventinal system to cope with the demands of h/water being used alot in the church hall canteen,4 days a week.It is flying out tons of hot water and is one superb boiler. Keston c55

 

[hedsa]

Give it a year or two your opinion about kestons will change . They leak for fun.

 

[gas4you]

Frank, do a search on here for Kestons, you will find that perhaps you are the only one who thinks they are good

Typical Ideal back up and quality

 

[bengasman]

Frank, do a search on here for Kestons,

Typical Ideal back up and quality

I learn something every day. When did those two join forces? I don’t suppose this is a case of trouble shared is trouble halved.

 

[frank uk]

Really? I thought they were superb,the whole thing i liked from the flue to the casing.I am really suprised,by your replies.I have fitted 5 and now i wait for the leaks to start. Is the c55 a culprit as well

 

[gas4you]

Frank, do a search on here for Kestons,

Typical Ideal back up and quality

I learn something every day. When did those two join forces? I don’t suppose this is a case of trouble shared is trouble halved.

Ideal bought them about 18 months 2 years ago.

 

[bengasman]

TA Dave

friend of mine is considering a keston, better warn her again

 

[JohnD]

although a new boiler will be more efficient, it can take you a long time to recoup the cost.

I used the BG site to see how I could improve my energy efficiency; one of the recommendations was that I fit a more efficient boiler. it would save me £105 a year and cost £2,500

So in 25 years it would have paid for itself

I'd get a better return than that in the building society.

the money is staying in my pocket unil the old boiler is irrepairable. When the time comes that I need a new one, the extra efficiency will be a bonus.

If your circulation is poor think about having it desludged and/or a new pump and/or a new 3-port valve (old one might be leaking pressure into the cylinder) depending on what the cause is.