Heat pump / inverter DIY

paceinternet

How are the ASHP's running today? Well particulalry those of you in the areas getting very heavy snowfalls most of the day, and sub zero temperatures.

Are defrost cycles more frequent and are they reducing the temperatures you can maintain inside the house?

Any other comments/observations would be appreciated.

richardc1983

Hi Paceinternet

Well my unit outside is covered in snow, would like to upload photo to here of it but cant, can email it to those interested though!

There is also snow building up behind and in front of the unit however I dont think its affecting airflow. One thing I have noticed is the unit seems to be sucking snow into the coil so its instantly freezing on the coil, defrost times have increased i.e the length of a defrost cycle seems to be 10minutes. (normally about 5minutes) I think this is because it then takes longer for the preheat to get the coil back upto temp after defrost. During which time the internal temp drops very quickly due to having terrible insulation and draughty double glazing (victorian house & high ceilings no wall cavity = cheap conversion into flats). I have found the inside temp cannot increase above set point of 22C (which im comfortable at however im sure if I left it on 23C and high fan speed it would get there. But obviously with the defrost cycle it has to get from about 21C to 22C again but it does it within about 20 minutes and then holds it there for a few hours till the next defrost cycle.

Electric consumption has also increased. Used nearlly 19units of electric for yesterday, not sure about today yet it doesnt download till midnight.

I do know though that having the ASHP on is better than the central heating, I have massive double radiators in all rooms and the boiler is a new boiler and set to highest flow temp but still it only manages to get the temps upto about 21C maximum.

My units are oversized for the rooms as well so im thinking the fact they are oversized is a good thing as they are coping with the low outdoor temps.

It feels cruel when your warm inside and you have a unit outside working hard to extract heat from the air!!! But its only a machine!

Andy_WSM

paceinternet wrote: »

How are the ASHP's running today? Well particulalry those of you in the areas getting very heavy snowfalls most of the day, and sub zero temperatures.

Are defrost cycles more frequent and are they reducing the temperatures you can maintain inside the house?

Any other comments/observations would be appreciated.

I can report similar to Richard. It is sub zero out (-3C) with heavy snow fall which has settled around the outdoor unit. As I type the unit has gone to defrost mode, however, the house is at a very cosy 23C which is the current set point, so still running spot on. Power consumption has risen slightly, but not massively so. I think if the unit wasn't running 24/7 then it may have struggled the last couple of days, because like Richards, mine is sucking in the falling snow - so probably spending twice as long on defrost as it normally would. Maximum consumption today according to the meter is 1912W (1.9KW) - which considering this is heating the whole house is great. Total consumption today is 30Kw (approx £3.60)

richardc1983

Hi Andy

So your saying the max wattage drawn today is 1.9kw but total for the day USED is 30kw?

This would mean that yours is using pretty much the same as mine. My unit isnt on 24hours a day instead comes on when the central heating goes off @ 08am and goes back off when it comes back on @ 5pm. WHen the central heating goes off the house is probably only at 18C maximum so it then has a fight to get the room upto temperature. REmember the walls, and furniture absorb all the heat so it has to bring them upto the set point and with it being an old house it would struggle. Is your unit using similar during the night or do you lower the set point in the night when you have gone to bed.

I sometimes set to 18C overnight if I know im in the next day but because im on a £1 meter its awful for it to just be burning away.

I know the unit if left on 24hours a day would maintain any set point if needed.

Would anyone like to see a pic of the outdoor unit? If so send me your email address!

Andy_WSM wrote: »

I can report similar to Richard. It is sub zero out (-3C) with heavy snow fall which has settled around the outdoor unit. As I type the unit has gone to defrost mode, however, the house is at a very cosy 23C which is the current set point, so still running spot on. Power consumption has risen slightly, but not massively so. I think if the unit wasn't running 24/7 then it may have struggled the last couple of days, because like Richards, mine is sucking in the falling snow - so probably spending twice as long on defrost as it normally would. Maximum consumption today according to the meter is 1912W (1.9KW) - which considering this is heating the whole house is great. Total consumption today is 30Kw (approx £3.60)

richardc1983

Oh and Andy how much are you paying per unit?

Cardew

Andy_WSM wrote: »

which considering this is heating the whole house is great. Total consumption today is 30Kw (approx £3.60)

Andy,

I would agree that 30kWh is excellent and costs are in the same region as a good gas CH system(approx 100kW)

Richard states that his in the same region as yourself.

Yet Stevehead with two units left on 24/7 in a 3 storey house during a very cold December and January has averaged about 10kWh a day - one third of your figure.

I just find that puzzling!

richardc1983

Cardew

My system and Andys system are no where near the efficiencys of Mitsubishi power inverter. Mitsubishi sell 2 product ranges for the inverters. They have standard inverter with usual COPS but then they have the Power Inverter which are even more efficient (dont know how they do it) and Steve has the Power INverter range.

My equipment is made by LG and is a commercial system. Andys from what I gather is a budget system.

WOuld be interesting to know what the capacity of Andys system is.

I have two units connected to an outdoor unit where total heating capacity of outdoor unit is 8kws. Obviously if only one unit is operating it will be half that.

My indoor units are both 3.5kw but can max out at about 8kws when first turned on.

The only thing I can think of is that steves units are obviously a. more efficient & b. lower capacity than mine and Andys.

He may only have 2 x 2kw systems which would total 4kws so this possibly may be the case. Obviously the units wont be running flat out all the time.

To advise the electric consumption is an estimate. I have taken off what I think I have used roughly for other electrical applicances, fridge freezer, cooker, microwave, tv, lighting etc.

Andy_WSM

richardc1983 wrote: »

Cardew

My system and Andys system are no where near the efficiencys of Mitsubishi power inverter. Mitsubishi sell 2 product ranges for the inverters. They have standard inverter with usual COPS but then they have the Power Inverter which are even more efficient (dont know how they do it) and Steve has the Power INverter range.

My equipment is made by LG and is a commercial system. Andys from what I gather is a budget system.

WOuld be interesting to know what the capacity of Andys system is.

I have two units connected to an outdoor unit where total heating capacity of outdoor unit is 8kws. Obviously if only one unit is operating it will be half that.

My indoor units are both 3.5kw but can max out at about 8kws when first turned on.

The only thing I can think of is that steves units are obviously a. more efficient & b. lower capacity than mine and Andys.

He may only have 2 x 2kw systems which would total 4kws so this possibly may be the case. Obviously the units wont be running flat out all the time.

To advise the electric consumption is an estimate. I have taken off what I think I have used roughly for other electrical applicances, fridge freezer, cooker, microwave, tv, lighting etc.

I have a Fujitsu Inverter system which is ducted into each room, so I would expect to use a bit more power as I have no cold spots - and guess I lose a small amount of heat in the loft through the ducts? I also pump a lot of heat into the conservatory which is totally inefficient but needs to be kept warm as my tortoise enclosure is kept in there - and they like heat more than I ! This is my model: http://www.ultimateair.co.uk/pdf/Jan%2007%20Update/Current%20Single%20Split%20Service%20Manuals%20Mar06/Ducted%20+%20Universal%20Concealed%20Units%20Service%20Manuals/ARY18-24L%20Service%20Manual.pdf

Oh, right now there is 4 inches of snow on the ground, the outside air temp is -4C and the indoor temp is 21.5C against a set point of 23C, so struggling a little today, but then so would my old Gas heating system if it were still alive.

richardc1983

Oh of course Andy!!! THat is the link I gave you!! HAHA

Have you got Outdoor unit AOY18 or AOY24? One states 6.20kw heating and the other states 8.00kw heating.

Which one is yours?

It is very cold outside today, one thing I dont understand is that these systems quote that they work down to -15 and at -15C should still have 80% of their heating capacity.????

Andy_WSM

richardc1983 wrote: »

Oh of course Andy!!! THat is the link I gave you!! HAHA

Have you got Outdoor unit AOY18 or AOY24? One states 6.20kw heating and the other states 8.00kw heating.

Which one is yours?

It is very cold outside today, one thing I dont understand is that these systems quote that they work down to -15 and at -15C should still have 80% of their heating capacity.????

AOY24 Richard. I don't ever believe the figures quoted. That said, mine in pumping out plenty if heat for only a 1.44Kw draw at the moment. I think the house is slightly colder because of the losses through insulation and low outdoor temps rather than lack of heat from the A/C. 8Kw of heat isn't a huge amount in this sort of weather, but it seems to be sufficient.