Massive Gas Bill, Change 2 Old Gas Boilers for 1

AmberGold

Just got a whopper of a gas bill, 1K for the last two months. Haven’t been frugal with usage and was also at home for 2 weeks with COVID during the freezing spell & isolating in the attic room which is the coldest in the house.

House is a 2005 build, 2700 sq ft over three floors and has two S28 mini, Ideal Gas boilers, one boiler for hot water and one for rads. Although old they’re humming along and have been recently repaired and serviced.

Now looking at the usual stuff including reducing usage, additional loft insulation and new seals on some windows.

I’m seeing a lot on the net about new condensing boilers being 20% more efficient. Also considering putting rads and hot water on one boiler. Anyone any advice on whether I’ll see savings from the boiler / config change?

MicktheMan

Hi AmberGold, I made the following comment in another thread recently and it might also directly relate to your query and save you from having to upgrade your heating system especially since you mention an attic room.

"Looking at this from a slightly different angle (and not really answering your questions directly), the reason for needing a heating system is to replace heat lost from the house. Perhaps there are opportunities to make a decent impact on the heat loss side of the equation which could considerably reduce the need for heating so a simpler heating system would suffice.

Not talking about insulation upgrade here per se but the big one for most houses is heat loss by air leakage. How to know is to have a pressure test of the house perhaps as part of an overall heat loss survey. Next address the low hanging fruit based on the test results and then revisit your (lower) heating needs."

shane b

I have a similar sized house built in 2004 but it's a dormer bungalow and we had to get a new boiler in April 21. It cost around 4k to have fitted. We needed a boiler that had 2 flow and 2 return pipes so that limited our options boiler wise.

If there is plumbing work to be done you could be looking at 2-4 k for a new boiler.

Do you have any budget in mind for these works or expected payback period?

As the poster above mentioned figuring out where your heat is going and stopping that may be more cost effective.

ongarite

You can make some small changes that can save probably €100 of that bill.

Reduce temperature by 1C across all zones. Turn down gas boiler temperature by 5-10C. Running at 65C for example can save nearly 10% on gas usage if you have a condensing boiler as the return temperature will be in ideal range.

Shauna677

A €1000 gas bill is crazy, was heating on day and night. Did you not know gas prices are through the roof :-( i wouldnt spend that amount in 2 years. Was your meter read or is it estimated bill.

wotzgoingon

https://www.boards.ie/discussion/comment/120045133#Comment_120045133

Really two years. I do not have gas so cannot compare but it costs close to that to fill the oil tank and it would not last two years I can tell you that. I turn it on if I'm cold for a hour or so and then off and may do that throughout the day and for a few hours in the evening time. It's off now for over a hour and I'm not cold. And will not be turned on again for the rest of the night. But as I said the oil tank would not last two years so I do not know how you can mange that unless you are in a small bedsit or something and not a full house either 3 or 4 bedroomed.

AmberGold

https://www.boards.ie/discussion/comment/120045133#Comment_120045133

The house is larger than the norm, we also heat the water with gas, 3 teenagers that like long showers + baths. The Nest settings might not have been ideal either. It wasn’t on all the time thou. We have a few rooms that are always cold + I suspect air loss. I was very aware that prices had increased but was still surprised at the bill. I was expecting €600 or so based on last year.

Re other comments, thanks, I’ll be getting an air leak test asap.

DataDude

https://www.boards.ie/discussion/comment/120045335#Comment_120045335

Honestly, as mad as it sounds, that bill doesn’t sound unusual to me - especially if you’re trying to keep all/most of the house relatively warm through that cold spell.

We live in a slightly bigger house of a similar era. Was previously 2 boilers. Now 1.

For a house that size you’ll need a 35kw boiler to run water and radiators. Assuming you pay c12c per kWh of gas, it’ll cost you just over €4 per hour to run the boiler. So even running the heat 4 hours a day (which I suspect won’t keep your house that warm unless it’s relatively well insulated) will cost you over €16 per day, or c.€1000 per billing period.

Unfortunately just the reality of living in a large house which isn’t super modern.

Shauna677

https://www.boards.ie/discussion/comment/120045178#Comment_120045178

no I also live in older 1700 sq foot house that has been super insulated. 4 bedrooms, last bill was 169 euro, granted i got 40% off with Bord Gais. Only put on gas heating for few hours and house is sweltering, it also heats the water. A stove in living room is lit in the late afternoon.

I had oil in a previous house, a tank used to last about 10 mothns but that house was was far less insulated.

Burti16

I have similar size house with BER B3 rating. Triple glazed windows and foam insulated attic. I also have two heating zones with smart thermostats that control downstairs and upstairs separately. So, everything looks great on the paper but I paid 320 EUR from 8 Dec to 1 Jan. It's insane amount and never paid this much in my life. Here is my findings

- My thermostats were keeping house at 22C 7/24. We have a new born baby so can't compromise heating. I reduced downstairs to 21C and boiler heating this area only from 6 am to 9.30 pm.

- reduced upstairs from 22 to 21.5. Upstairs are always 21.5. So boiler barely kicks in for upstairs .

- I found out that 15% of total heating is going for keeping hot water tank warm. I reduced temperature from 60 to 50. I can hear that boiler barely kicks in to heat water with this setting

- type of boiler. I'm planning to install condensing boiler this summer. I had Worcester boiler in my previous house and most of the time it was heating house without using any gas. I'm not pretty sure about the technology but it is using waste gas or something to re-heat water.

AmberGold

https://www.boards.ie/discussion/comment/120075640#Comment_120075640

Yep that sounds like us without the foam insulation. I’ve moved the nest to a table beside me and I’m now manually adjusting it based on feel. Surprised at the variance between temp shown on the nest and how warm or cold the room feels. Usage has decreased dramatically.

I’m also getting a company to do a heat loss survey and will upgrade the attic insulation at the very least. According to the engineer I spoke with getting the boilers changed won’t lead to significant savings.

Ush1

https://www.boards.ie/discussion/comment/120045376#Comment_120045376

35kw could easily be oversized, would need to do a heat loss calc on the property. You really don't want a boiler running at it's max output especially for long periods.

Zoning may help depending on the living patterns and layout.

Current system with two boilers sounds fairly inefficient.