Heat Pumps as main heating...?

[daddymac]

Thanks Richard! I take your point! The Guy with the newsagent wants cooling in the summer more than anything as the heat damages his stock.

[Peter_1]

When we build our house, we installed 2 Viessman hetapumps, air/water.

After 2 winters, we replaced them with a gas fired burner and I'm still happy I did it.

In the offices I worked for +/- 1,5 years ago, they installed a Mitsu VRF. After already one winter, they were already looking for another way of heating. Far too expensive.
It depends of course of the price you pay for a kWh compared to the gas price.

On the other hand, heating a bedroom is now not that difficult.

And a cheap unit is not per definition a power consuming or a noisy unit. Saw Shinings with Daikin compressors in it, Saginomya 4 way valves and pressostat, and the rest is a normal battery/coil and a casing. The bigger it can be the better it will operate.

Can someone explain me why Mitusbishi is keeping it's HP in teh VRF's at +/- 16 bar (R407c) in cooling mode when it's 15°C outside and EEV's are fitted in the indoor units and the condenser fan is humming at a very, very low speed?
What is the benefit of this? Why not running on al ower HP when it's possible?

And the PCB's, well the less there are in it, the better. They should better replace them with a cheap Logo of Siemens and give us the software.

[frank]

Hi Peter

Could it be that the HP is kept high to ensure good liquid circulation to the EEV's on the indoor unit's ? or to control sub cooling.
With high HP and low fan speed the condenser will not back up with liquid. I suppose it is how the software is written to cope with all different indoor loads.

Is it a 2 pipe heat pump system or a heat recovery system?

[Peter_1]

It's a PUHY so no recovery.
Having EEV's is just the benefit where you don't need a high HP.
Subcooling, well they can do this - perhaps it's done this way - by adding a subcool section in their coil.
Or subcool it mechanically.
And perhaps a bigger receiver (is there anyaway a receiver in it?)
I think because they use it to determine if the unit is filled correctly by heating small resistances in the receiver or in some sort of receiver.

It should increase the COP of the unit a lot.

Did someone recalculated ever the COP of the unit with the figures in the technical manual?
I have here in front of me the leaflet of a PEAD-P6EA/ OUtdoor 0°C Indoor 20°C= COP 2.6 but this is number is valid when the unit is running.

If the unit defrost each hour for 5 to 10 minutes, the (expensive) electrical heater is then also coming up to prevent cold down draft and in some occasions add heat so that the compressors can find somewhere the necesarry heat to defrost the coil outside, stops then afterwards the whole cycle some minutes when switching the reverse cycle back to heating and then needs first some minutes to cool down the indoor unit to an acceptable level where the indoor fan can turn on again... well, the overal COP will drop enormous.
The whole defrosting cycle last at least 15 minutes (counted from start defrost till indoor unit is back again on full heating capacity)

[Temprite]

G'day all

Most houses around the area here are heated with heat pumps.

The only available gas supply is from bottles. If there was mains gas available you would probably find more people using it..

We install mainly Daikin, which seem to handle low ambients quite well. It hardly ever gets below 0 deg c in winter here..

[daddymac]

Peter_1
These "Shining" machines you mentioned... where can I get more info? Do they have a UK agent?

[Peter_1]

www.shining.nl

[fixit]

Hi Temprite

Most houses around the area here are heated with heat pumps.

We install mainly Daikin, which seem to handle low ambients quite well.

Which modle of daikin and how do you connect to the heat to the house

Ps. I am looking for an inverted heat pump, (air to water)know of any?

[Temprite]

Hello fixit.

We install mainly single high wall splits, ceiling cassettes, multi splits and some ducted units.Mostly inverters.

I dont know of any water source heat pumps by Daikin.

[Peter_1]

I am looking for an inverted heat pump, (air to water)know of any?

Clivet, Rhoss, Daikin, Carrier, Trane, McQuay,.......