Replacing gas boiler

Hi, my old (19 years) ng central heating boiler has just given up the ghost and I need to replace it. I live in 4 bed det hse near Dun Laoghaire. There are four adults in the house and high demand on the showers several times a day. Also have a dishwasher. Currently there are ten radiators attached to heating system, most of them large doubles.

Got a quote from Bord Gais installer for a replacement boiler, a new (factory insulated) copper cylinder, 2 thermostatic valves and to resite the boiler from its present position (in the integral garage) to the hotpress upstairs (vented out into the sidepassage) for just under €4,000.

However, have discovered that the quote is for a boiler with a "D" energy rate so not too happy with this. Rang back the installer who quoted for the job but he said this was only relevant to England and that the high efficiency condensing boilers were not suitable for our house. Didn’t explain why.

The house has mainly old gun barrel piping which I plan to have replaced within the next year when a major refurbishment job is being done. Most of the rads have gun barrel piping although some have copper piping (replacements over the years). Most of the rads have thermostatic valves on them. There is a copper cylinder with a lagging jacket in the hotpress. There are two showers, one electric and one heated from the cylinder.

Have been reading the threads and it seems that a modulating combi condensing boiler with an "A" rating might be the right choice for me. This would mean that I could fit the boiler into the hotpress and get rid of the copper cylinder.

Any advice on –

Is it a good idea to get a combi condensing boiler while the old gun barrel piping is still in place? I am afraid that the pressure may cause leaks. I cannot change the piping at the moment but don't relish the idea of having no heating until the refurbishment is completed.

Also concerned about the showers. It seems that if I get the combi boiler the cold water tank in the attic will no longer be in use. How will this affect the two different showers and the dishwasher/washing machine - both cold fill?

It seems from what I have been reading that if the new boiler is connected with the cold tank in the attic that I might have a problem with any dirt that is in the cold tank getting into the new boiler. How could I deal with this.

Is there anything else that I should consider?

Please also suggest some models and where they can be obtained. I have looked at www.rvr.ie but do not know which makes to consider. Also, if I order a boiler online, where could I get a qualified person to install it.

Sorry this is so long and many thanks.

I have a similar situation-except our piping is copper.I want to replace boiler with something better and more efficient etc.The installer that called today-the third one i have spoken to- said he would only install a condenser boiler in a completely new system.He reckoned I wouldnt get the full benefit of it in my system.
He did get a bit technical-but in the end convinced me-to go for something else.

A condensing boiler is no problem for any type of heating pipe. But if the old type of heating system was a low pressure system ( the ones with a tank in the attic) then the concern if the pipes would hold the higher pressure is justified.
New plastic pipes aren't expensive. But if you employ a plumber to lay them then the worktime beeing charged for this job could be a surprise.
If you aren't born with two left hands then a good DIY book will help you to understand what's involved and you might decide to do the job yourself. It's no space science.Try "Collins DIY book" for example.
Modulating combi gas condensing boilers can be bought in the DIY shop for about €600.- (in B&Q) or for a bit more in any plumber shop ( or example "heatmerchants").
Try the Sedbuk page for a good choice on what's available, see http://www.sedbuk.com

well thanks for your input-having spoken now to 3 different heating installers-and also read yor input-it would make for an interesting conversation between them and you.Each of them had differering views and I doubt that any of them would agree with your comments.DIY? I think I,ll stick with wallpaper and paint.

I would advise you that condensing boilers do have their downsides (as do all heating systems). So before you set your heart on a condensing boiler maybe talk to someone about the other options and their suitability for your hot water demands and heating needs!

As far as I know, a condensing boiler will only work in condensing mode if the return temperature (the warm water coming back to the boiler) is low - i.e. 30-40 deg C. Most old systems work on 81 deg C coming out of the boiler, and returning at 72 Deg C. To get to 30-40 deg C, you need underfloor heating, or very very big radiators.

The effect this would have is if your AA rated condensing boiler is fitted into an old system (72 Dec return temp), it won't work at AA efficiency levels, it may be reduced to A/B/C or even the D level that your installer has quoted for.

I paid 2800 for a new boiler (standard boiler) and had it moved from the chimney into the hopress. I live in a small 2-bedroom house, and it warms up soo quickly, I've got the boiler at the lowest setting and the valves at low settings... The installer had predicted that and I had looked into the condensing boiler option as well, but like you and others was advised that you don't automatically get the best out of it, so as unfortunate and Bootdog are advising, look into it more before you go for it.

All boiler sold at the Sedbuk rating "A" are working on that efficiency band. Bring that company to court if it doesn't, they would have to cover the full costs occured to you(solicitors, fuell bills, building works etc.) if you had been cheated.
What neither Bootdog nor Petal have understood is why this is so.
One has to compare like with like, that is boiler with boiler, under the same conditions, serving the same heating system in the same building.
And that makes the condensing boiler more efficient then the old outdated non-condensing boiler.
A condensing boiler that has to deliver 80 degrees for a badly insulated house with undersized radiators has to deliver 80 degrees flow temperature.
And the old banger has to do so as well, delivering 80 degrees.
But the condensing boiler's fluegases would be only 80degrees hot.
Whilests the flue gases of the old banger would be several hundred degrees hot. Wasted energy. Blown up into the sky.
Sorry for you, but you have been cheated by a salesmen.
A condensing boiler delivers energy at the set temperature and uses the fluegases to achieve this temperature. The old banger uses the flame only, not taking care to what can be got from the fluegases as well. The condensing boiler has a larger,more efficient heat exchanger then the old banger. That's simple physics. But the law of physics are not the strenght of the plumber, he knows the laws of selling:find an idiot and make something of it...(No Insult!!)

Bootdog said:

As far as I know, a condensing boiler will only work in condensing mode if the return temperature (the warm water coming back to the boiler) is low - i.e. 30-40 deg C. Most old systems work on 81 deg C coming out of the boiler, and returning at 72 Deg C. To get to 30-40 deg C, you need underfloor heating, or very very big radiators.

The effect this would have is if your AA rated condensing boiler is fitted into an old system (72 Dec return temp), it won't work at AA efficiency levels, it may be reduced to A/B/C or even the D level that your installer has quoted for.

Click to expand...

THis sounds like a fairly fatal flaw for condensing boilers. Can anyone else comment on the accuracy of this claim or the likely impact?

I've been quoted €2,600 for fitting an 80,000 BTU condensing system boiler (including pump). Is this good or bad?

Some info here from manufacturers [broken link removed] that suggests that these boilers only operate in efficient condensing mode with return temperatures below 57 degrees.

More here from the Canadian : "For the condensing boiler's heat exchanger to extract all the potential latent heat effectively, the system has to run with the lowest possible return water temperatures, preferably not exceeding 45–50°C (113–122°F). Unfortunately, most radiator systems are designed to operate at significantly higher return water temperatures, which makes it difficult for the flue gas to condense. If the return water temperature is too high, actual operating efficiency may be only slightly higher than that of the better models of non-condensing boilers. "
Leo

Hi Guys, I think of replacing my 10+ year old gas boiler to a new condensing one.

I am getting quotes in the range of 2700Euro. I dont know if it will be better to buy the boiler myself online from rvr and get a quote from a local plumber to install it. In that case will I have to get an inspection done by a registered installer after the installation? Any suggetions please.

Thur, Did you get the new boiler installed last year? Was it a condensing one?

Thanks, Tom.

I want to replace my 100k BTU 5 year old gas boiler with a 100K condensing one and a plumber has quoted €2,800 for supply and fit of a Weissmann one. Also he quoted €11,000 for underfloor heating in a ground area of 9m x 8m and supplying a nw 300L cylinder and pump. I have no idea if this sounds a reasonable price. Can anybody advise me? I have only been able to get 1 quote to date as all plumbers are too busy!

Can anyone tell me anything about patterton suprima 50L boilers. I just had one fitted yesterday and after looking it up on the internet am very worried as there is nothing good said about them. If they're as bad as the things I've read I'm wondering why any plumber would fit them. I know nothing about boilers so would be trusting the plumber to put in one that wasn't going to be trouble.