New gas boiler, your thoughts welcome

Yes the intention is to have the boiler run the hot water as well.
At present we have a large tank that heats twice a day on the heures creuses. Always seems far too hot for me, and more than we need.
The radiators are old and large but very olid. A couple of engineers have said they should be fine once they’ve had a good clean out and some new valves put on.
Thanks very much for the link.

Sorry, I’ve no idea what they are. We just have a small/medium garden.
There is a garage roof that is south facing.

But aren’t there thousands of urban households running on gas? Are they all going to be forced to change?

Our quote came in at 17k!

The government announced earlier in the year that oil-fired boilers would be phased out in ten years so it’s safe to assume the same announcement for gas boilers will follow suit sometime in the not too distant future IMO. Governments are becoming greener and greener to win more votes so fossil fuels are on borrowed time I feel.

In the UK there is a backlash against woodburners. Do you think that will happen in France? We’ll freeze if they get blacklisted.

Unless you spend around 45% of your electricity during hours creuses, the increased tariff the rest of the time you loose. Might be ok if you get an electric car.
The water must reach 60 for legionella destruction that’s why it’s hot but you are supposed to reduce it with a blending valve close to the tap to reduce the risk of scalding

The UK has introduced an emissions standard but its a low threshold - any stove manufactured in the last 10 years should exceed it. There is no standard in France as far as I know.

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That’s good because we want another woodburner for the kitchen.
We like pellet burners but think the pellets would need too much room for storing.

Not really good as the emissions standard is for good reason, you breathe cleaner air, room sealed apart from opening the door to re fuel.
EU regulations on emissions from stoves in 2022

None of my friends with pellet stoves have special storage space, they buy a few sacks when they need them. Great heat output, programmable timing.

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We currently live in Cyprus but are hoping to move to Gers sometime next year. We have looked at many houses just so that we can get a feel from prices etc.
One of the most important factors for us will be the method of heating, if the primary heating is electric then we don’t look any further.
If the property has a wet system run from a gas or oil fired boiler we would 100% set some money aside to modify the system to run on an air to water heat pump.
The water flow temperature from an air to water heat pump is generally capable of reaching 60C, your radiators will most probably been sized on a flow and return temperature of 80/70C. For this difference your radiators for the heat pump would need to have approx 30% increase in surface area to provide the required out put, they could be changed to double panel and finned so that the pipe connections don’t need to be changed.
However, LG have a high temperature unit that will provide a flow temperature of 80C so no need to change the radiators.
The most important factor for an air to water heat pump is that the maximum heat output is around 16kW. If you have heat losses greater than this then a heat pump won’t be good enough.
With the level of insulation in new houses then heat pumps are the future. 1kW power in and around 4kW heat out.
If replacing your current system with a heat pump is a possibility then I’d give it serious consideration, it will be a massive factor if in the future years you want to sell up.

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Yes, you can get 60°C flow from an air sourced pump but the CoPs drop significantly - 3 to 1 is probably realistic at that high a flow temp, even with fairly warm (i.e above 10°C) intake air.

I’m no expert - just an “interested” owner of a heat pump system but I’ve posted quite a bit of data on these because there is much more to sizing a heat pump than just looking at the “headline” CoP and max heat output figures.

That said, although they are not perfect air source heat pumps are a good way to heat a home if you want to have a moderately “eco friendly” solution.

I’d be very interested to know the exact model of the LG you mentioned - at some point I’ll be looking to change the boiler in the UK and had started to toy with whether I could make a heat pump work here, having access to a high flow temperature if it does not impact efficiency too much moght be useful.

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Don’t let go of what you know, whilst they can reach higher temperatures flow and efficiency must drop, law of physics. Marketing in ideal laboratory conditions etc.

My guess is that 80°C can only be reached with auxiliary heating - in fact 60° can probably only be reached with additional heat. My heat pump has a 6kW heater, it isn’t there for decoration.

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The model for the higher temperature LG unit is the Therma V high temperature unit. It can reach a flow temperature of 80°C by using two stages of cascade compression. It doesn’t need any auxiliary heating but the COP is considerably less and may be only 2.1. This is still going to be more efficient than oil or gas but I’m really not sure it would be worth it unless your main concern was your carbon footprint.

If these units did have any form of auxiliary heating, then this would have to be taken into account in the quoted COP values.

With any air to water heat pump, they are best operating at low flow temperatures to get the best COP, so typically 45°C for radiators and 35°C for underfloor heating, so if you have underfloor heating then it’s the perfect most energy efficient method of heating with a COP approaching 5.

All of the COP’s stated by all manufacturers for their heat pumps and the like are under perfect conditions where you will get the best COP readings, so -3°C to 10°C outside conditions to the lowest flow temperature possible.

The only way you will find out how efficient these units actually are is to install one to determine the true efficiency over an entire year (seasonal efficiency). Apart from that you’ve got to consider what flow temperature you are going to run at and understand that the COP quoted is the best possible and in reality you just aren’t going to get that. It’s a bit like the quoted mpg values for cars.

It’s a difficult choice to make, heat pumps are ideal for new builds but an awful lot needs to be considered for a retrofit in an old property.

OK, yes - manual here, There seems to be just one high temperature unit in the range which has a CoP of 2.61 at both A-2W65 and A7W65 which is reasonable I suppose. Otherwise CoP’s seem to be just over 4 with 7° air and about 2 with -2° air for a 55° flow temp - again not radically different to any other unit on the market.

I did some back of the envelope calculations in the previous thread which suggested a “seasonal average” CoP of 3.6 would reduce your COs footprint by about 20% but probably cost more to run than a gas boiler - at least in the UK, for mains gas.

Your comments re underfloor heating being well suited are spot on, of course - as are your observations that it’s a complex decision if replacing a conventional boiler in an existing system.

We have looked at a Jotul and I would like a hotplate on whatever we get if only to put a kettle on. Any recommendations or what to avoid would be welcome thanks.

Yes Paul, the law of diminishing returns, usually linked to the inverse square law at which point friction takes the rest.
I believe we’ll need a break through in tech to get to the next level. Rather like the breakthrough Toyota have made, by accident that a li-ion battery can be vastly improved with titanium. not bad for a company that thinks batteries won’t make it so back hybrid.

More efficient air-con units using a desiccant are on the way so only logical something in the heating dept could follow.

I am still considering evacuated tube array for pool and underfloor in winter with a small top up of some kind.

Anything with a flat top and not made in France for the last 100 years should suffice.
Worth looking at the DEFRA site for recommendations of cleaner burning more efficient stoves. Plenty of Jotul’s and others.

The EU stove alliance regs due in 2022 should shake up the market but I doubt some countries will change despite rules.

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Thank you.