Keep oil condensing boiler or switch to air to water?

tonc76

I'd appreciate advice on the following:

Renovated a 70s bungalow (120m2) in 2016 to include new plumbing throughout (10 rads and a Firebird enviromax popular 20kW), cavity pumped, all external walls slabbed, 300mm attic insulation and kept double glazing windows that had been fitted in 2009.

I'm now looking to build an extension to include en suite and walk in wardrobe for main bedroom and increase the size of the kitchen/living area (~50m2 all in but opposite ends of the house) so probably add another 2-3 rads to the system.

Am I better off to add to the existing oil fired system or convert to air to water?

From a cost perspective how much can I expect to pay yearly for air to water?

What are the pros and cons of each option?

Tom44

Boiler can be ajusted up, but only by a competent service engineer.

adam88

tonc76 wrote: »

I'd appreciate advice on the following:

Renovated a 70s bungalow (120m2) in 2016 to include new plumbing throughout (10 rads and a Firebird enviromax popular 20kW), cavity pumped, all external walls slabbed, 300mm attic insulation and kept double glazing windows that had been fitted in 2009.

I'm now looking to build an extension to include en suite and walk in wardrobe for main bedroom and increase the size of the kitchen/living area (~50m2 all in but opposite ends of the house) so probably add another 2-3 rads to the system.

Am I better off to add to the existing oil fired system or convert to air to water?

From a cost perspective how much can I expect to pay yearly for air to water?

What are the pros and cons of each option?

Is this your standard Irish bungalow?? Sitting rooms, front door, 2/3 bedrooms out the front and kitchen bathroom and usually one room out the back. Rectangular job. I’m doing similar hopefully starting next year p

tonc76

adam88 wrote: »

Is this your standard Irish bungalow?? Sitting rooms, front door, 2/3 bedrooms out the front and kitchen bathroom and usually one room out the back. Rectangular job. I’m doing similar hopefully starting next year p

Yeah something like that. I think they're was a grant available for houses up to 1300 sq ft at the time so lots of bungalows come in just under that!

corkgsxr

If find it believe air to water will be near as efficient as oil in that situation

adam88

corkgsxr wrote: »

If find it believe air to water will be near as efficient as oil in that situation[/quote

I think so myself. Air to water works on the premise that the house has to be prett much air tight. Every aspect of the house would need to be A1, floors included.

tonc76

Thanks for the replies with some really good points to consider. Reading through them I should have given more info.....

What I'm trying to figure out is in the long run am I better to change to air to water now when I will have building works going on or should I just look to add to the existing OFCH syetem (the boiler was purposely over sized when installed as we were always going to build on).

Also any ideas on the annual cost to run air to water as would be good to compare v annual oil cost/maintenance and calculate how long it would take to get a return on investment? I realise that the cost of oil and carbon taxes will rise so it'll be a rough calc.

Latro

To generate the same amount of heat energy with heat pump will cost you about 40% of oil. That's a rule of thumb.
The HP generates low temperature heat though so you need large radiator area to make it work.

If you will try to use it the same way like you you do with oil or gas it will not be as efficient. Instead of short blasts of heat it should be run 24/7 but the focus should be on lowering the flow temperature as much as possible.

Most people here will tell you that in order to install HP you need very low energy loss. This is a fallacy.

I can tell you for sure. As the house is more air tight and better insulated the heat loss is approaching zero and less sens it makes to invest into expensive heat generator.

corkgsxr

Latro wrote: »

To generate the same amount of heat energy with heat pump will cost you about 40% of oil. That's a rule of thumb.
The HP generates low temperature heat though so you need large radiator area to make it work.

If you will try to use it the same way like you you do with oil or gas it will not be as efficient. Instead of short blasts of heat it should be run 24/7 but the focus should be on lowering the flow temperature as much as possible.

Most people here will tell you that in order to install HP you need very low energy loss. This is a fallacy.

I can tell you for sure. As the house is more air tight and better insulated the heat loss is approaching zero and less sens it makes to invest into expensive heat generator.

I like to see that in reality in a average older house. Imo you'll burn through the electricity trying to sustain heat

sydthebeat

the Heat Loss Indicator is a good measure of whether your structure is suitable for a Heat pump or not... as, obviously, putting an electrical fuelled heat system into a house thats pi$$ing heat out through the elements is non sensical.

you should get in touch with a technical advisor to assess your house, even if your not going for a grant

https://www.seai.ie/publications/Technical_Advisor_Role.pdf

Latro

corkgsxr wrote: »

I like to see that in reality in a average older house. Imo you'll burn through the electricity trying to sustain heat

And would it be any better with oil? To sustain same amount of heat will cost you 2.5 times more than with heatpump.

John.G

At normal oil/gas costs then IMO the saving, depending on the energy requirement, is approx as shown in the S.Sheet (do your own calcs), ironically, the less you use, the less the saving, so again IMO very hard to justify retrofitting A2W, a new build yes.

Wearb

Latro wrote: »

And would it be any better with oil? To sustain same amount of heat will cost you 2.5 times more than with heatpump.

The way oil is used is very different. People rarely keep the house at a constant temperature, rather they let it cool down at night and/or when away at work. Because of the relatively quick heat up time with oil / gas this works ok.

This would need a -perhaps- 20+kw heat pump and huge rads to achieve the same heat up time. Otherwise it means keeping house constantly at about 21C, negating somewhat the heat pump savings.

That's my thinking on it anyway. I need to say that I'm no expert on heat pumps. Just observations in houses of family members.