Heat pump / inverter DIY

richardc1983

Do you leave it operating at 23C 24/7 or do you lower the temp at night?

I guess heat loss in the house is a big factor? Set your fan speed to high in the colder weather as the full capacity of the unit is only output in high fan speed!

Andy_WSM

richardc1983 wrote: »

Do you leave it operating at 23C 24/7 or do you lower the temp at night?

I guess heat loss in the house is a big factor? Set your fan speed to high in the colder weather as the full capacity of the unit is only output in high fan speed!

I turn it down most nights, but left it on 23C last night as I had been out playing in the snow (taking photos!) and got cold
I leave the fan set to auto actually and the unit seems to make a good job of picking the right speed. The set point will be reached shortly. By the time I have had my shower it will be there, it's already picked up just from the heat generated making toast, boiling the kettle etc - the ducted system of course reuses this heat elsewhere too.

richardc1983

When you say ducted and uses heat elsewhere what do you mean uses heat elsewhere?

All systems have return air. For instance my unit isnt ducted but has a return air side that sucks air from the room in to return it back to the unit to be conditioned.

Your system due to being in the loft has to have ducts to remove the air from the rooms it recirculates the air.

Or do you have something else that brings in fresh air from outside but doesnt vent the hot air from inside the house to the outside>?

Andy_WSM

richardc1983 wrote: »

When you say ducted and uses heat elsewhere what do you mean uses heat elsewhere?

All systems have return air. For instance my unit isnt ducted but has a return air side that sucks air from the room in to return it back to the unit to be conditioned.

Your system due to being in the loft has to have ducts to remove the air from the rooms it recirculates the air.

Or do you have something else that brings in fresh air from outside but doesnt vent the hot air from inside the house to the outside>?

No, I mean the former - and by "uses heat from elsewhere" I only mean that instead of letting the heat from a hot kitchen, or steamy bathroom escape (by opening a door or window as you might do normally) it picks the heat up via the return (in each room) and mixes it back in with the air from the rest of the house. It's more efficient than letting the heat escape through a window or cooker hood etc and by the time it is mixed it doesn't get spewed into the rooms as "damp air" because of the quantities involved.

richardc1983

I understand now. Thought u had installed heat recovery system also.

Well I have gotten home, central heating has heated the place upto 19C this morning, were -1.6here and the ASHP is walking along at 1000w with a 22C indoor temp.

I think I will leave at 22C as this is a nice temp for me, if i go chilly its because I refuse to put extra layers on hate wearing jumpers.

I get too hot if any warmer especially if im moving about the place cleaning etc.

Hermann

Cardew wrote: »

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!

Perhaps construction of house, insulation, draughtproofing and efficiency of Heat pump play a part.

I would think the difference between a 'near to ideal' situation and a 'far from ideal situation' would make a significant difference to running costs.

richardc1983

Have just posted this in another post thought would be worth putting in here:

Heres some info about inverters, the same applies across all manufacturers however efficiency levels are different but the operation side of things is the same.

Click here to view more info on heat pumps... its the Mitsubishi New Zealand/Australia site but some interesting articles on heat pumps.

http://www.bdt.co.nz/comfortmaster/support.asp#info

Some info on inverter technology.

Location:

Indoors:

Don’t locate units with obstructions in front.

Result:


Short cycling of air back to units room sensor making the unit think its wamer/cooler than it actually is.
Air is not circulated correctly leaving cold/hot areas in room.

Try to locate the indoor unit where the airflow is pointing to the other areas of the house that may require residual heating/cooling.

Outdoors:

Avoid paved areas unless a drain kit is fitted. Result: Units condensate and drip water. May cause slime build up or ice. If no other place please advise customer.


Inverter System or Fixed Speed System?

What is a Fixed Speed Split System?

This system only has a single speed compressor motor that is either on or off.

It works similar to a fan heater that switches off when the desired temperature is reached and on again when the temperature drops to a set level. It speeds up or slows down to calculate the heat loss from the space to be heated ensuring it is only putting in the same ammount of heat that the space is losing.

What does Inverter Mean?

Inverter technology uses a variable speed compressor motor similar to a car. It simply slows down and speeds up as needed to hold a selected comfort setting.

Inverter technology provides a more precise room temperature without the temperature fluctuations of fixed speed systems.

Inverter vs Fixed Speed:

Inverter Systems are Approximately 30% more efficient than fixed speed systems.

Inverter systems reach desired room temperature quicker.

The speed control of the outdoor unit also means quieter operation, this is important especially at night in residential areas.


Inverter Systems

• Increased output to achieve set temperature faster.
• Then varies the output to maintain a constant room temperature.

Fixed Speed Type

• Slowly gets to temperature as output rating is fixed.
• Then turns on and off to maintain room temperature.

samtheman1k

punamulta wrote: »

as the UK air is damp i would expect units to frost up even at above freezing air temps, as the compressor will drop below freezing and the moisture in the air will freeze on it. As long as the unit has an additional reverse defrost cycle on the outside unit it should be ok.

not all units for sale here have that, so check before buying.

This is correct. Our Air/Water Ashp (Mitsubishi ecodan) regularly goes through a defrosting cycle, perhaps once an hour. As the heat exchanging fins are many degrees below the surrounding air, they regularly freeze over and the HP reverses it cycle for just a few seconds to blow all the ice off. You don't notice any difference to the usage of it though as it only lasts a few seconds.

richardc1983

I am now needing to install another unit onto my multisplit outdoor unit, I already have the wall mount unit just need to get it installed.

If anyone knows anyone in the trade that would like a bit of extra cash can you let me know.

anthonykeates

richardc1983 wrote: »

I am now needing to install another unit onto my multisplit outdoor unit, I already have the wall mount unit just need to get it installed.

If anyone knows anyone in the trade that would like a bit of extra cash can you let me know.

Out of interest Richard, why do you feel the need to install an extra unit - is the flat not warm enough, or is it just to help with heat distribution?

If I go ahead, I'm thinking in my flat a fairly hefty unit to heat lounge (20ft by 17ft, 10ft ceilings and 7 double glazed windows!) plus another in the main bedroom which would blow out into the hall/bathroom as well. Would leave the second bedroom/study as unheated directly. Whaddaya reckon?

I've got a rather lame layout plan drawn on Paint but I can't work out how to attach it to the post at the moment!