Air to Air Vs Air to Water Heatpumps. Now closing the gap.

[Ivor Windybottom]

Have you got a relatively new and well insulated house?

Myth. It doesn't make any difference. You can run a heat pump or gas boiler, or any other heating system in a well-insulated or uninsulated house. It's irrelevant. Any heating system will be more efficient in a well-insulated house.

Ours is a 1950s bungalow. Reasonable loft insulation, blown-in wall insulation from about 30 years ago, old windows and an uninsulated concrete floor.

We're lovely and warm with our heat pump. If I spent £10,000s on replacing the floor and cladding the walls then I might save £200 a year in electricity, it would make absolutely no sense to do it unless I lived to the age of 1000.

 

[Peter.N.]

Its much cheaper to keep our 350 year old stone cottage warm with oil with oil. If you buy your oil at the right time of the year it costs 5-8P per Kwh, our electricity is 30P per Kwh!

 

[Highway Man]

Here is the air to air system breakdown costs, showing just how much a saving you can make, it is a larger system than mine so mine is super efficient to run and has convinced me to invest in a solar battery system to run my air con units.

 

[Dec27]

Myth. It doesn't make any difference. You can run a heat pump or gas boiler, or any other heating system in a well-insulated or uninsulated house. It's irrelevant. Any heating system will be more efficient in a well-insulated house.

Ours is a 1950s bungalow. Reasonable loft insulation, blown-in wall insulation from about 30 years ago, old windows and an uninsulated concrete floor.

We're lovely and warm with our heat pump. If I spent £10,000s on replacing the floor and cladding the walls then I might save £200 a year in electricity, it would make absolutely no sense to do it unless I lived to the age of 1000.

It’s not a myth as such. The heating source has to be able to supply enough kWh to heat the property.

And air source heat pumps are mainly less than 8kw.

 

[warey4life]

Myth. It doesn't make any difference. You can run a heat pump or gas boiler, or any other heating system in a well-insulated or uninsulated house. It's irrelevant. Any heating system will be more efficient in a well-insulated house.

Ours is a 1950s bungalow. Reasonable loft insulation, blown-in wall insulation from about 30 years ago, old windows and an uninsulated concrete floor.

We're lovely and warm with our heat pump. If I spent £10,000s on replacing the floor and cladding the walls then I might save £200 a year in electricity, it would make absolutely no sense to do it unless I lived to the age of 1000.

My house is 1880s with large rooms and high ceilings, it has double glazing but gets quite cold in the winter. We have a newish boiler and rads in every part of the house except for the kitchen where have underfloor heating. I think we'd struggle with a heat pump.

 

[Ivor Windybottom]

Its much cheaper to keep our 350 year old stone cottage warm with oil with oil. If you buy your oil at the right time of the year it costs 5-8P per Kwh, our electricity is 30P per Kwh!

A heat pump would reduce your electricity heating cost by a factor of 3. We're currently paying 20p a unit on a fixed tariff, so we're effectively paying 7p a unit for our heat.

This is what many people don't understand - a heat pump doesn't produce heat using electricity, it uses the electricity to move the heat from the outside air to inside. If you stand in front of the fan of our outdoor unit it blows out really cold air - as the outside air it sucked in has had lots of heat removed from it, which has been transferred into the circulation water and is spewing out of our radiators. It's not magic, but it's really clever and is sadly too complicated for many to comprehend. Whereas everyone understands setting fire to stuff, so it's the natural fall-back option.

Nobody should be paying 30p a unit for domestic electricity, unless it's part of a complicated tariff that's much cheaper at other times.

 

[Ivor Windybottom]

It’s not a myth as such. The heating source has to be able to supply enough kWh to heat the property.

And air source heat pumps are mainly less than 8kw.

Ours is 10kW (heat rating, using about 3kW of electricity), but up to 20kW (6kW electricity) is available even on single-phase.

There's no advantage to over-sizing, it's all done as a result of a survey of the room sizes, construction type etc. If you go too big then it will spend a lot of time switching itself off, then there's a loss of energy in restarting later. It's better to work it hard than to have it idling.

There was once a valid correlation between heat pumps and insulation - when they were puny little things that needed near 24-hour running to keep up. Ours is on and off on-demand, with the heat switched between zones at different times of the day. We treat it exactly like a gas boiler - it starts heating the various rooms about an hour before we'd typically go in them. It all works great and is very cheap to run.

I reckon ours costs about the same as mains gas. If mains gas was an option then I'd have weighed up the pros and cons. But we live in the countryside without mains gas, so a heat pump was a no-brainer. Oil or the other options are far more expensive.

 

[Ivor Windybottom]

My house is 1880s with large rooms and high ceilings, it has double glazing but gets quite cold in the winter. We have a newish boiler and rads in every part of the house except for the kitchen where have underfloor heating. I think we'd struggle with a heat pump.

You'd be fine. You may need larger radiators here and there. But you have gas and a newish boiler so there'd be no sense in changing.

Where gas is available, the smart way for new heating systems is to ensure it's all heat pump ready, i.e. big rads and pipework. This also means that a gas boiler can run at a lower flow temperature, saving you money from day one. But then when World War 3 starts properly, and gas prices go through the roof, you can then plug in a heat pump and switch over.

 

[Highway Man]

Ours is 10kW, but up to 20kW is available even on single-phase.

There's no advantage to over-sizing, it's all done as a result of a survey of the room sizes, construction type etc. If you go too big then it will spend a lot of time switching itself off, then there's a loss of energy in restarting later. It's better to work it hard than to have it idling.

There was once a valid correlation between heat pumps and insulation - when they were puny little things that needed near 24-hour running to keep up. Ours is on and off on-demand, with the heat switched between zones at different times of the day. We treat it exactly like a gas boiler - it starts heating the various rooms about an hour before we'd typically go in them. It all works great and is very cheap to run.

I reckon ours costs about the same as mains gas. If mains gas was an option then I'd have weighed up the pros and cons. But we live in the countryside without mains gas, so a heat pump was a no-brainer. Oil or the other options are far more expensive.

Couple up your heatpump to a battery system and you will be quids in.

 

[Highway Man]

The only reason why a gas boiler is cheaper to heat your home at the moment is from elictricity prices being 4 times higher. By utilising a solar battery system those costs go way down. If electricity prices were down everyone would jump on heatpumps. The way to get even better value and lower upfront costs is to fit air conditioning heat pumps and you get the benefits of heating and cooling as well as air purification. Utilise your existing combi purely for hot water . Win Win.

 

[Ivor Windybottom]

Couple up your heatpump to a battery system and you will be quids in.

I'm not convinced. We have a (small) solar array on our roof - 6 panels, about 2.5kW actual max. We buy leccy at 20p a unit on our current fixed tariff (all day/night). We sell our surplus at 13p a unit. We're usually selling power all day (when the sun's out), then buying it back in the evening.

So we effectively pay the grid 7p a unit to store our surplus power for us. You'd need a lot of 7p's to pay the £1000s that batteries cost. And even then you don't get it all back - you only get about 80%, the rest turns into heat through the various processes of charging/discharging. So you'll pay about 4p to store it in your own battery.

Then you need to consider that they will wear out over time. They don't work perfectly for 10 years then stop, they gradually get less capacity from day one. They may just break one day, probably outside of warranty.

They could also set fire to your house - not common, but possible. When we have to one day get a leccy car then I'm going to install it far away from the house via an underground cable, so a burning car won't set fire to the house. It's a tiny risk but one I'd prefer to avoid. Putting a massive box of batteries in the house seems a bit reckless to me.

 

[Ivor Windybottom]