Air Source Heat Pumps

paceinternet

Good analogy, but depends what you are having for lunch.
You can get lunch for £0.80 every day, but you might need to modify your cutlery and get a new plate, and there is a good chance you will always get your lunch.
You can get lunch for £1.00 every day, but you will need a new plate, and there is a good chance you will always get your lunch.
You can get lunch for £1.20 every day, and you can use your normal plate, but lunch might be coming from Russia or the Middle East and not always be available, and could vary in price, and although it is organic, there may be some knock on effects to the surroundings when you have eaten it.

stevehead

Cardew wrote: »

'No such thing as a free lunch'

Talking of free lunches - and slightly OT - these 'radiator boosters'
http://www.nigelsecostore.com/acatalog/Radiator_Booster.html
mentioned elsewhere on MSE but I can't find the thread.
Obviously I can't swallow the 'save up to 50%' bull, delicious as it is, but I can add a pleasant desert.

I'm going to build one of these simple things, but run the fan off a peltier generator stuck to the radiator. This eliminates the need for a power socket near the radiator, and self regulates without the need for a thermostat.
I had to pay for lunch, but I'm too tight to leave a tip :-)

richardc1983

Swipe wrote: »

I received my electricity bill today. I'm very impressed. I used just £49 for the period 23rd July to 19th Oct. That includes 3 weeks or so of using at least one of my ASHPs most evenings for 4 hours.

It's currently 12C outside. My living room air source heat pump is maintaining an indoor temp of 19C and drawing just around 300w. I'm also adding an extra 170mm of loft insulation this weekend and getting a new sitting room patio door in a couple of weeks. Combined with my ASHPs and multifuel stove (lots of free wood), I'm looking forward to 70% lower electricity bills this year compared to my previous house (heated via storage heaters) last winter.

HI Swipe

What output is your heat pump? Im sure we have discussed this before, my system being a multisplit unit is designed to run 4 units and thereffore the compressor cannot run any lower than 800watts on heating.

richardc1983

stevehead wrote: »

Talking of free lunches - and slightly OT - these 'radiator boosters'
http://www.nigelsecostore.com/acatalog/Radiator_Booster.html
mentioned elsewhere on MSE but I can't find the thread.
Obviously I can't swallow the 'save up to 50%' bull, delicious as it is, but I can add a pleasant desert.

I'm going to build one of these simple things, but run the fan off a peltier generator stuck to the radiator. This eliminates the need for a power socket near the radiator, and self regulates without the need for a thermostat.
I had to pay for lunch, but I'm too tight to leave a tip :-)

I thought of inventing something like that once but didnt bother as didnt think people would be interested.

Its similar as pointing a fan blowing onto a radiator.

Swipe

richardc1983 wrote: »

HI Swipe

What output is your heat pump? Im sure we have discussed this before, my system being a multisplit unit is designed to run 4 units and thereffore the compressor cannot run any lower than 800watts on heating.

It's a 3.5KW single split unit. I have two of them, one in the living room and one in the bedroom.

richardc1983

Would you say the units are oversized for the rooms they are in, ours are purposly oversized so we can run them in low fan speed all the time and have extra duty shud we need it.

Swipe

richardc1983 wrote: »

Would you say the units are oversized for the rooms they are in, ours are purposly oversized so we can run them in low fan speed all the time and have extra duty shud we need it.

The bedroom one definitely is. One guy told me I would only need a 2.5KW in there but I insisted on a 3.5KW so I could leave the door open and heat the hallway. The living room one is probably about right @ 3.5KW for a 21m sq room with 8ft ceiling. I'm not sure what the formula is to work it out. Any idea?

Edit; just done a heat loss calculation and it says my living room only requires a 2KW input. So yes I'm oversized. This means I can leave the doors open and heat the whole house. I heard bad things about oversizing for cooling but I don't use them in summer as the bungalow is nice and cool.

richardc1983

Swipe wrote: »

The bedroom one definitely is. One guy told me I would only need a 2.5KW in there but I insisted on a 3.5KW so I could leave the door open and heat the hallway. The living room one is probably about right @ 3.5KW for a 21m sq room with 8ft ceiling. I'm not sure what the formula is to work it out. Any idea?

Edit; just done a heat loss calculation and it says my living room only requires a 2KW input. So yes I'm oversized. This means I can leave the doors open and heat the whole house. I heard bad things about oversizing for cooling but I don't use them in summer as the bungalow is nice and cool.

Here you are: Heat load calculator

http://www.climate-facilities.co.uk/air_calculator.asp

And yes mine are oversized so I can leave internal doors open and heat the hallway, kitchen and bathroom! Works a treat!

richardc1983

Swipe wrote: »

I heard bad things about oversizing for cooling but I don't use them in summer as the bungalow is nice and cool.

That is really based on fixed speed systems they would run at full output whether required or not so they would short cycle and therefore cool the room too quick, which means the room would be cool but it wouldnt have time to remove humiidy. The inverter systems will ramp up and down based on what duty they require as you already know so doesnt really affect cooling operation like in fixed speed.

Do you find your units run constantly in heating or do they cycle off at all, mine still cycle off but thats down to the large outdoor unit that can only ramp down so far... its supposed to run 4 units and only running 2.

Swipe

richardc1983 wrote: »

Do you find your units run constantly in heating or do they cycle off at all, mine still cycle off but thats down to the large outdoor unit that can only ramp down so far... its supposed to run 4 units and only running 2.

If I leave the doors open they run constantly but they do cycle off once they reach set point. It's at that point when they do kick back in they are just ticking over at 300watts. I only heat to 19C so they reach set point very quickly when it's mild. I have a log burner in my living room for weekends when it's really cold. When that's running my pump will be turned off.