Balanced coverage?

[AE-NMidlands]

https://www.theguardian.com/money/2021/ ... ng-outside (At home with a heat pump: ‘It makes hot water when it’s freezing outside’) is interesting. Seems to be saying "Don't buy cheap."
I am interested to hear that they are now delivering quite hot water as there is no way we could put underfloor heating in, and I'm not sure the radiators could be enlarged much either.
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[nowty]

Well I may have to resurrect my old thread on me installing a ground source heat pump in 2018 and running it in parallel with my existing gas boiler so I can use either to heat my house and water. Works fine with outside temp down to about 3 degrees and works great with solar, batteries and cheap off peak tariffs. Typically consumes between 1.5kW and 2.3kW depending upon output water temperature. Achievable COP between 3.8 and 2.5 depending on output water temperature.

Total cost, around £3k, but a lot of work !

8kW heatpump (real world 6kW) - Ex-display but as new £1,000. In comparison a new similar Kensa one would cost £6,000+
300 litre stainless steel heatpump cylinder with twin immersions - bought brand new from bankrupt plumber for £500. Normally £2,000.
Bespoke home made copper ground source heat exchanger (heat extracted from underground water source) - £250
Water pumps - £300
Control valves, thermostat, etc, - £100
Pipe and fittings - £300
Additional radiators in house to increase efficiency. - £200
Timber, insulation, etc, - £200
Additional immersun (second hand) for diverting excess Solar PV - £200

[Stinsy]

This is one of those topics where it is seemingly impossible to get a balanced opinion!

“Chocolate fireguard” vs “Best thing since sliced bread”.

Stories such as those claiming “piping hot water” and “rads always hot” with low bills are simply untrue. The more these lies are spread the worse the reputation of heat pumps will be. Such stories should include the electricity bill for the house concerned.

A correctly-sized heat pump will work in a well-insulated house when the outside temperature is between 0-15 degrees anytime the temperature is lower heat output will reduce and you will need auxiliary heating to maintain , often a resistive element built into the heat pump. Resistive heating is extraordinarily expensive. An undersized pump or poorly-insulated house will resort to resistive heating even more.

An over-sized pump will work better at lower temperatures but cycle more in mild weather. A wood burner or other non-resistive auxiliary source of heat is a good idea for unusually col weather.

[Joeboy]

I was what sapping a mate today who has a 2 year old house. Quality build and he was saying horrendous amount of power consumed in Winter and said same as stinsy re cost of heating element to top up house heat. I'd love to be convinced and make plans to change out my GCH boiler for a ASHP but it just doesn't seem to be there yet. I also wonder as we are both in NE Scotland if the real temp difference has truly been taken into account for our Northern sites when sizing is taking place? Can these units be overspecced to perform in harsher climes and have an easier run to themselves the other 6 months. Just a thought or 2....

We can easily see 2 months straight with neg temps..I just could not see myself replacing a standalone system that can do the whole job(gch) with a system that needs another source to help it along. I happily await being shot down in flames and told why I should go ashp and part of me wants that.

[nowty]

This is one of those topics where it is seemingly impossible to get a balanced opinion!

“Chocolate fireguard” vs “Best thing since sliced bread”.

Stories such as those claiming “piping hot water” and “rads always hot” with low bills are simply untrue. The more these lies are spread the worse the reputation of heat pumps will be. Such stories should include the electricity bill for the house concerned.

Absolutely, what I can tell you is mains gas is (unfortunately) still cheaper to heat my house unless I am running the heatpump from Solar PV or 5p off peak Octopus Go tariff and maybe a few extra hours on batteries. So in winter it can only be used for several hours a day unless I want to pay more.

However gas usage at nowty towers has dropped from a whopping 28,000 kWh when I had the original non condensing scaled up gas boiler in 2010, to 22,000 kWh in 2011 when a modern condensing boiler was installed.

With the heatpump from 2019, gas has dropped to between 5,000 to 8,000 kWh depending on how much I use the heatpump or boost the storage heaters on cheap rate. But sacrificing the gas any further means higher bills, no two ways about it, and people must understand that.

The ripple wind turbine will incentivise me to use more leccy and even less gas, so I might get the gas down to 3,000 or 4,000 kWh. If I was allowed to buy even more of the ripple windfarm I probably could get down to some really low gas levels.

Or another way of looking at it all is I remember my combined gas/leccy bills were about £2000 a year in 2010. Now with all the Solar PV, better insulation, batteries and heatpump my combined gas/leccy bill is about £700. With the ripple wind farm that might drop to about £400. The cherry on top is that now includes charging the EV whereas before it had to be filled with petrol. And the even bigger cherry is the £3000 a year in FITs income.

[Countrypaul]

This may be useful to someone, as it is real world experience, location Yorkshire dales, family of 4. No gas to the house.

We have an ASHP, but also UFH and a thermal store, most of the time the ASHP runs off E7 electricity.

When we were looking for the ASHP we were told on more than one occasion that the temperature which they had to use to calculate heat demand was dependant on location in our case they used a value of -3C iirc. They also based the heat load of the house on the EPC which was probably very pessimistic. We have had no problems with the ASHP producing enough heat even in depths of winter (though we have only had a few coninuous days of sub zero temperature). The ASHP heats a 430L thermal store and the UFH is driven off the TS with individual thermostats in most locations on the ground floor. The first floor only has UFH for the bathrooms. The thermostats are set such that the target temperature drops once the E7 period finishes, so we are using both the TS and the screed (70mm S&C over 125m2) for storing heat.

There is an 11.2kW Mitsubishi Ecodan which I suspect is probably oversized for the house, however it does not stop and start that often probably due the TS. The house is about 225m2, orginally built 1957, but renovated finishing 2018, so I would suggest well insulated and quite air tight. There is a MVHR system, this is one aspect that I think needs modifying, as when it is 0C outside and 20C inside the supply air to the rooms is only 17C which tends to be very obvious in the bedrooms (no heating) so am looking to put a duct heater run off the ASHP in place this autumn (I started a thread on this recently). The supply air temperture drops as the outside air temperature drops so if 20C difference inside to outside gives roughly 17C supply, if -4 outside the supply drops to 16C etc.

We also have a 3.3kWp PV system and an Eddi, but as yet the Eddi does not turn on the ASHP when there is surplus PV (job for this summer), it does divert to an immersion heater at the top of the TS.

We have no need for any additional heating backup (there is no resistive heater in the ASHP). The only time we have suffered from the ASHP not keeping the house warm was when someone (we never worked out who) presumably accidently turn it off. It took 2 days before we realised we had a real heating problem and about another 2 days before we had thigs back to normal. The UFH runs at about 25C on the ground floor. I believe the ASHP uses 4-5000 Kwh per year (but may be January before I can be sure due to incorrect initial setup - yes 60C output temperature!).

I have heard that ASHPs are popular in Scandinavia where temperatures drop well below what we normally experience (even in Scotland) so strongly suspect that most problems come from incorrect sizing in the first place, exacerbated by lack of understanding on how to get the best out of them (which is not by runing then a gas boiler). It would be interesting to know how much training/explanation of how to use the heat pump is given to those that opt for one without the understanding that most on this forum would have. Turning the ashp to run at 60C output to heat the house up and then off and on at 60C is definitely going to result in excessive electricity usage and high bills.

[Joeboy]

A lot of interesting info here. Many different systems/structures to achieve a greener way of doing it and bill killing at the same time. I reckon I'll be keeping a close eye on ashp tech and doing more research before I just auto change out for best GCH system boiler, thanks CP I'll know more next Spring once we've seen how the woodstove/battery stack/ ripple /storage heater combo all play out over a Winter together. I'll have to achieve gull knowing as it's too much upheaval and cost to turn out a choc fireguard!

I share the £2,000 dropping to £650 home fuel bills but now including car fuel benefits of Nowty, sadly only about £400 in FIT but taking into account £1,500 saved from fuel and we are deeply into neg FF costing compared to the old days. Gotta say I love that coil into the underground stream, killer app!

[Stinsy]

A lot of interesting info here. Many different systems/structures to achieve a greener way of doing it and bill killing at the same time. I reckon I'll be keeping a close eye on ashp tech and doing more research before I just auto change out for best GCH system boiler, thanks CP I'll know more next Spring once we've seen how the woodstove/battery stack/ ripple /storage heater combo all play out over a Winter together. I'll have to achieve gull knowing as it's too much upheaval and cost to turn out a choc fireguard!

I share the £2,000 dropping to £650 home fuel bills but now including car fuel benefits of Nowty, sadly only about £400 in FIT but taking into account £1,500 saved from fuel and we are deeply into neg FF costing compared to the old days. Gotta say I love that coil into the underground stream, killer app!

You are surely at the “heat pump” stage of your journey!

You’re also in a good position to dump gas because your wood burner can take up the slack in a really cold spell. Might I suggest an air-to-air as a good way to ease yourself in?

[nowty]

I share the £2,000 dropping to £650 home fuel bills but now including car fuel benefits of Nowty, sadly only about £400 in FIT but taking into account £1,500 saved from fuel and we are deeply into neg FF costing compared to the old days. Gotta say I love that coil into the underground stream, killer app!

If your new and wondering what the coil in the underground stream is, its this,

[AE-NMidlands]

Have we all got one of them? During a confined space control course I was on the N Irishmen called it "lumpy water!"
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