Air Source Heat Pumps

[Vanordinaire]

mcbook said:

Thanks Vanord, that's really helpful information. I'd expect to have a similarly sized water tank so that detail is especially helpful.

What happens to the loan and RHI if you want to move house?

Still seems like it uses quite a lot of electricity though...

Applicant is liable for the loan until it's paid off. RHI stays with the house, so bear that in mind if selling up and price accordingly. We won't be moving, built the house to retire in.
Our ceilings are 13' high so on top of a reasonable floor area, its a fair bit of space to heat. You have to remember we only have a electricity bill, most people have heating and electricity to pay. I don't think its bad compared with a combined gas and electricity bill for a similarly sized house.

[Jambo85]

Lemming Train said:

No, it really isn't. Your heat is being stored! There is no 'on demand' function to it, is there? It's Economy 7 for the year 2019. If you haven't "stored" enough heat then tough st, you're out of luck and you're not going to be having a hot shower, bathing the kids and doing a load of washing whilst mooching around your toasty 20C gaff in your T-shirt.

LT, I think you’re seriously misunderstanding something, or greatly exaggerating? Aside from the floor screed and building fabric (not insignificant admittedly) there is no storage aspect to normal ASHP installations.

[dhutch]

mcbook said:

Regarding the fabric of the house, I agree that it's worth doing this right. There's a lot to still to be decided but my preference at the moment is to have the structure factory-built and assembled onsite by the manufacturer, including windows. Put them on the hook for airtight-ness, hopefully doing it this way will help ensure quality but we'll see.

A right, so its a timber frame / sip type construction rather than bricks and mortar?

garyhun said:

Just so I’m clear, I assume you’re saying conventional plaster because it’s a quality thing for you?

Assuming bricks and mortar, which it might well not be, it improves air-tightness, the ability re-work and repair rooms, doesnt fall to mush if damp, but yeah might also be a personal thing and certainly I am sure you can bond plasterboard well. I have not commissioned a house but I have seen some awful dot & dab. Far to easy to hide so much behind it!

caziques said:

Claiming a heat pump is a 2019 version of storage heaters is complete bks.
There are 10kWhrs of energy in a litre of heating oil, hence 1 kWhr costs about 5p in the UK.
If electricity is 12p per kWhr, a heat pump will cost 4p per kWhr (if the heat pump is 3:1).
ie the running costs are comparable

Equus said:

...Except that running costs are not the only criteria to consider.
Some people value flexibility, and this is where heat pumps fall flat on their ass.

garyhun said:

You’ve been away on holiday and just come back to your house. It was warm when you left so turned all the heating and hot water off.
Now there’s a cold snap and you need the house warm as quick as possible and a tank of water for the family to have showers later on.

To me this is all under the same heading a does fit together.

With a well insulated house, you keep it warm all day, the losses are small, and all is well. This works with night storage (cheap energy put in a night, released through the day) or with ashp/gshp where you have low level heating all day and you can leave it on if your away for a week because the heat loss it trivial anyway. Happy days. Scandinavian.

If the house is poorly insulated, pishing heat out any time its other then cold, the all of a sudden you create a mindset and need to only heat the house when you need it warm. So night storage, and low level base heating system of ashp/gshp all go to the wall and the running cost goes through the wall because while the cost of energy is on a par the amount of heat lost is double what it would be if you only heated it from 6pm to 10pm.

Daniel

[ecs]

What are the options available for people wanting to get rid of LPG? Our barn conversion has a terrible underground LPG tank installation, it's been installed below the water table and the manhole floods instantly meaning that 9 times out of 10, Flogas will turn up and refuse to fill it. That and LPG is pretty expensive!

We've looked into an air source heat pump, but we don't want to have to install larger radiators in all of our rooms and an underfloor heating retrofit would be hugely disruptive. We're currently looking into air conditioning - my parents are converting a barn into offices and a dwelling and they're having a ducted central air system which uses inverter heat pumps.

We're looking at installing a 4kw solar system on our south facing roof, but this will only really help us in the summer so I don't think an electric boiler will be much use (for context, we have a swimming pool which is electrically heated with an inverter heat pump).

Does anyone have any experience with biomass boilers? Is this a better alternative to LPG?

[Equus]

dhutch said:

To me this is all under the same heading a does fit together.

With a well insulated house, you keep it warm all day, the losses are small, and all is well.

To a degree... but the temperature of the house is only one half of the equation.

The other half is that human beings are finicky biological things, not machines. Our comfort zones vary (and not just by temperature, but humidity and air velocity). You spend many hours studying this, on an Architecture degree (or at least you did back in my day).

As an example (and I appreciate that I might be a bit weird) I tend to prefer a very cool internal temperature when I am in bed - I sleep with the windows open, even in winter (and the back door open, so that the dogs can come and go as they please). First thing I do when I get up on a morning, in winter, is to bang the central heating on full to get the temperature up from maybe 4C to 18C.

In the afternoon, I walk the dogs and get back wanting a temperature of ~16C, so I tend to purge ventilate again (AKA leave the back door open for a bit).

I'm an ASHP's worst nightmare, in other words - and yes, I know I'll have the bunnyhuggers foaming at the mouth over the amount of energy I waste.

[dhutch]

Vanordinaire said:

In a previous life I worked for a social housing provider and was involved in researching, trialling, specifying, monitoring, and evaluating various alternative heating systems. I've been to several courses and seminars on the subject and have some practical experience.

Our final conclusions at work were that in the right situation, a properly specified ASHP system can be cheaper to run than anything else other than mains gas so where, for practical or environmental reasons, mains gas is not an option, air source is worthwhile considering. We, however, had no existing properties where it was worthwhile retro fitting air source . I believe (since I left that job) that on the basis of my research, the organisation has gone on to successfully include ASHPs in some off gas grid new builds.

That's very interesting. Sort of fits with the forum chat and heresay, but nice to hear it from someone who has actually made a career out of it. I spent a weekend renting and airbnb from a live in couple and she ran a gshp company and while the main plan of the day was my 30th we did have a bit of a chat about her work, which has some sale spin but also some fairly frank conversations about the downfalls of poorly integrated retrofits.

Vanordinaire said:

I've fitted an ASHP to my house. It's a 250m2 single story farm steading conversion on a Scottish hillside 300m above sea level.

In a previous life I worked for a social housing provider and was involved in researching, trialling, specifying, monitoring, and evaluating various alternative heating systems. I've been to several courses and seminars on the subject and have some practical experience.

We've been keeping the building at 19°C throughout November to now,occasionally through some pretty chilly weather. My electricity usage was ridiculously high ( £20 per day) at first with virtually no insulation in the
building then as I've completed each room, has come down steadily. Almost finished now ( still got some insulated plasterboard on the ceilings to do) and it's down to about £4 per day. Getting close to Nibe's estimate of £1200 per annum. That's with 4 adults living here at the moment keeping whole house at 19°C and a 300litre hot water tank at a constant 55°C. Hot water is via the ASHP but we also have a 3kW immersion heater which I leave on at all times. The heat pump alone is supposedly able to heat the 300l tank from cold in under 30 minutes, but as it doesn't seem to make much difference to the consumption, we just leave the immersion on too. Haven't ever been lacking in hot water.

Not sure what the underfloor pipework cost as I did it myself at the same time as doing everything else but probably around £3500. The pump and everything else associated was done by an approved installer for just under £10000. Being in Scotland, I can get a 10 year £10000 interest free loan for the system and I can also get around £1300 per annum free money for 7 years via the government's RHI scheme.

Conclusions:- Works for me in my situation, doesn't make sense for everyone.

Also very interesting. And nice to see it working for you.
Presumably the immersion is a lot higher in the cylinder than the ashp coil.

[dhutch]

Equus said:

To a degree... but the temperature of the house is only one half of the equation.

The other half is that human beings are finicky biological things, not machines. Our comfort zones vary

Fair enough, each to their own maybe. However having grown up in a house that is heated from underfloor night storage, actually I really get on with having a house that's just a nice temperature and where turning the heating off for 24hours make that little difference its only 48hour in you notice. Somewhere around the 19deg mark on the ground floor, maybe 18-17 on the first floor. If you want to be warm you put a coat on, when you go to bed its a bit cooler.


Daniel

[Lemming Train]

Jambo85 said:

Lemming Train said:

No, it really isn't. Your heat is being stored! There is no 'on demand' function to it, is there? It's Economy 7 for the year 2019. If you haven't "stored" enough heat then tough st, you're out of luck and you're not going to be having a hot shower, bathing the kids and doing a load of washing whilst mooching around your toasty 20C gaff in your T-shirt.

LT, I think you’re seriously misunderstanding something, or greatly exaggerating? Aside from the floor screed and building fabric (not insignificant admittedly) there is no storage aspect to normal ASHP installations.

Hence why I wrote "stored" as I did. They need heat from the air in order to work. If your house is Baltic then there's virtually no residual heat to convert to gas which in turn means there's nothing to condense to produce any new heat, so in very simple terms if you don't already have some heat already "stored" in the air in your house then you're not going to be getting toasty any time soon. Of course I'm fully aware than no bricks are involved (the old 70s storage heaters) but the complete lack of any form of 'on demand' heating is akin to how it was 40+ years ago when most properties had storage heaters and where Economy 7 originally stemmed from, hence the reference.

[Equus]

dhutch said:

Fair enough, each to their own maybe.

As an aside: I once worked for the property department of a major local authority. We had a number of care homes that were equipped with very sophisticated heating systems that reacted to the weather, and maintained a perfect temperature profile (cooler at night) at all times, with telemetry that told us the temperature back at the office.

We had endless complaints from the care staff, that places were too hot or too cold. We solved them by fitting 'thermostats' that they could adjust themselves, whereon everyone professed themselves happy. The thermostats weren't actually wired up to anything...

Sometimes the perception of control is more important than control itself.

[dbryder]

I don't have any professional qualifications, but had an ASHP installed in our 1880's Semi 5 years ago.

No mains gas was the driver for us, if there was mains gas I would not have thought twice and used that.

the biggest issue is getting a good system design, either do your homework or pick a good _experienced_ installer and you can make it work well (just as well as my previous gas fired heating in a new build flat)

Our electric bill is £100 a month which is heating, water heating, plenty of electrical hardware left in standby etc and we are not light users, the entire house is kept at 20 degrees (the system is off at night, but we lose around 1 degree during that time)

Happy to answer any questions I can.

[herewego]

Lemming Train said:

Jambo85 said:

Lemming Train said:

No, it really isn't. Your heat is being stored! There is no 'on demand' function to it, is there? It's Economy 7 for the year 2019. If you haven't "stored" enough heat then tough st, you're out of luck and you're not going to be having a hot shower, bathing the kids and doing a load of washing whilst mooching around your toasty 20C gaff in your T-shirt.

LT, I think you’re seriously misunderstanding something, or greatly exaggerating? Aside from the floor screed and building fabric (not insignificant admittedly) there is no storage aspect to normal ASHP installations.

Hence why I wrote "stored" as I did. They need heat from the air in order to work. If your house is Baltic then there's virtually no residual heat to convert to gas which in turn means there's nothing to condense to produce any new heat, so in very simple terms if you don't already have some heat already "stored" in the air in your house then you're not going to be getting toasty any time soon. Of course I'm fully aware than no bricks are involved (the old 70s storage heaters) but the complete lack of any form of 'on demand' heating is akin to how it was 40+ years ago when most properties had storage heaters and where Economy 7 originally stemmed from, hence the reference.

So you're proposing a system that uses a house's internal heat and multiplies it using the magic of condensation to make toast?

[Equus]

Lemming Train said:

If your house is Baltic then there's virtually no residual heat to convert to gas which in turn means there's nothing to condense to produce any new heat.

The point at which matter no longer contains any heat energy is -273 degrees Celsius.

It seldom gets that cold, even in the Baltic.

Don't be fooled by 0 degrees Celsius - that's just an arbitrary point, chosen to represent the freezing point of water.

[Vanordinaire]

Lemming Train said:

Jambo85 said:

Lemming Train said:

No, it really isn't. Your heat is being stored! There is no 'on demand' function to it, is there? It's Economy 7 for the year 2019. If you haven't "stored" enough heat then tough st, you're out of luck and you're not going to be having a hot shower, bathing the kids and doing a load of washing whilst mooching around your toasty 20C gaff in your T-shirt.

LT, I think you’re seriously misunderstanding something, or greatly exaggerating? Aside from the floor screed and building fabric (not insignificant admittedly) there is no storage aspect to normal ASHP installations.

Hence why I wrote "stored" as I did. They need heat from the air in order to work. If your house is Baltic then there's virtually no residual heat to convert to gas which in turn means there's nothing to condense to produce any new heat, so in very simple terms if you don't already have some heat already "stored" in the air in your house then you're not going to be getting toasty any time soon. Of course I'm fully aware than no bricks are involved (the old 70s storage heaters) but the complete lack of any form of 'on demand' heating is akin to how it was 40+ years ago when most properties had storage heaters and where Economy 7 originally stemmed from, hence the reference.

Sorry LT, back to school time. You've got ASHPs completely wrong. They don't use 'stored' hot air from inside the house, they use outside air temperatures and pressure from a pump to condense a liquid and the condensation process gives off heat which in turn heats up either air (air to air system) which flows into the house, or more commonly heats up water (air to water system) which is pumped either through radiators or through a network of underfloor pipes to heat the house.
They can work in outside temperatures well below zero and do give on demand heat.My system can give me 300 litres of hot water in under 30 minutes from scratch.

[anonymous-user]

What temp water does it generate Van?

[Vanordinaire]

garyhun said:

What temp water does it generate Van?

Currently set at 55°C, shouldn't really set it above 50°C but my wife likes hot water and it seems to manage it OK.

Edited by Vanordinaire on Tuesday 16th April 17:46

[anonymous-user]

Vanordinaire said:

garyhun said:

What temp water does it generate Van?

Currently set at 55°C

Hot enough for a bath then?

[Evanivitch]

Lemming Train said:

which means that it doesn't matter how many times you tell your builders you want it insulating up to the eyeballs, you'll get the minimum legally required standard, swiftly covered over with plasterboard and flooring panels whilst you're out of the way so you don't see any of it and then you'll be wondering why your house never gets above 15C and you're always shivvering.

So just to highlight LT's other issue, his criticism of Heat Pumps is that you can't trust builders? That's not a heat pump issue...

[Lemming Train]

Vanordinaire said:

Sorry LT, back to school time. You've got ASHPs completely wrong. They don't use 'stored' hot air from inside the house, they use outside air temperatures and pressure from a pump to condense a liquid and the condensation process gives off heat which in turn heats up either air (air to air system) which flows into the house, or more commonly heats up water (air to water system) which is pumped either through radiators or through a network of underfloor pipes to heat the house.

Right. Got my wires crossed then. I thought that they also "recycled" the residual heat from inside the house but on further reading apparently they don't and only get it from outside. So that makes them even less efficient as they are solely dependent on the outside ambient temperature.

My cousin had it installed in his detached place in a semi-rural part of Clitheroe around a decade ago and it has laid unused for at least the past 5 years because it's absolutely useless and now has oil central heating instead. I don't have much sympathy because he didn't do his research (his place is early 1900s so no insulation to speak of) and just believed what the sharp-suited salesman told him. Aside from it not doing any heating duties beyond luke warm I remember hearing the din of it screaming away constantly in his back garden and blowing ice cold air at you if you stood within about 10 ft of it, which made tending to his garden quite irksome.

Pleased to hear it's working for you but 1880s property and it producing 300 litres of hot water in 30 minutes? That is very much the exception rather than the rule.

[Skyedriver]

caziques said:

Lemming Train said:

ASHP/GSHP is the 2019 version of storage heaters with a fancy name. If you want to build your house with 40 year old redundant heating tech then go ahead but if the tech is so good then why are we not still using Economy 7/storage heaters still today instead of ripping them all out and replacing them with far superior gas/oil central heating with proper rads that are proven to work?

Don't pontificate about things you clearly know nothing about. Claiming a heat pump is a 2019 version of storage heaters is complete bks.

There are 10kWhrs of energy in a litre of heating oil, hence 1 kWhr costs about 5p in the UK.

If electricity is 12p per kWhr, a heat pump will cost 4p per kWhr (if the heat pump is 3:1).

ie the running costs are comparable - oil/gas are not "superior". Oil, gas, wood and heat pumps are alternatives, each have their place at the present time depending on circumstances.

With you on this, our ASHP provides perfect hot water and room temps (with the exception that one room is cool when the rest are fine due to the positioning of the stat)

[Skyedriver]

Vanordinaire said:

garyhun said:

What temp water does it generate Van?

Currently set at 55°C, shouldn't really set it above 50°C but my wife likes hot water and it seems to manage it OK.

Edited by Vanordinaire on Tuesday 16th April 17:46

Think you'll find that every two weeks it'll cycle up to 65 degrees to kill of any possibility of Legionnaires