Replacing gas boiler - BER C3 rating

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Replacing gas boiler - BER C3 rating
Just bought a house, built 2004, BER rating C3, 150 sqm detached.

Ferroli Tempra 24 gas boiler, BER says it's 78% water and space heating efficiency.

Two zones, i.e. two thermostats, upstairs and downstairs, no separate water zone.

One of the four showers runs off hot water, i.e. it isn't an electric shower.

Got an RGI to look at boiler, it hadn't been serviced, got it working, but the timer clock sparked.

So now no timer.

I would like to upgrade the boiler as I feel it's not the best.

RGI recommended Viessmans, it seems he is a registered installer.

• He said something like the 5yr warranty is extended to 10yr if he installs it, and services it.
• He mentioned 2,500 for boiler.
• He mentioned adding third zone on water cylinder.

This could all be a sales spiel, but they do seem like good gas boilers.

My questions:

(1) I read here that it's not much use replacing boiler unless house is well insulated. So am I wasting money on a new boiler with a C3 rating?

(2) Should I try to improve C3 rating first?

(3) Are Viessmanns a good boiler?

(4) What model would I need for 14 rads, of various sizes.

Vitodens 100-W or 200-W?

What KW output?

(5) I think I would qualify for the 750 boiler heating control grant?

I really, really appreciate any advice.

 

[Saavy99]

Hi

I paid €3000 to get a 26kw Vitodens 100-W combi gss boiler put into my house last summer. The old boiler was already taken out and price included the fitting and connecting to gas supply and water system as well.as certification. Precision is the company in Ireland that are the contract dealers for the vissmann boilers. Google them and they will give you contact details for approved contractors in your area. Definitely get more than one quotation, I was quoted an obscene amount with one company. My boiler is going great so far, it runs 12 radiators, I didn't go for the zoneing but the house is really well insulated.

 

[Leo]

I read here that it's not much use replacing boiler unless house is well insulated.

A new, more efficient boiler would actually pay for itself more quickly in a poorly insulated house where you need a greater heat output to maintain a comfortable environment. If your new boiler is more efficient and delivers the same heat output for 20% less gas consumption, then you can calculate how long it will take those savings to exceed the cost of the boiler based on your usage.

The argument about new boiler versus well insulated house is more one of if you have a certain budget to spend on energy efficiency, how do you get the best return or savings for that sum. In many, but not all cases you will get a better return investing in improving the insulation than you would by just replacing a boiler, but that doesn't mean a new boiler won't pay for itself over time.