Air source heat pumps

[superswill]

Gents

just putting the feelers out really on the above, looking at going this way to heat my new house (she made me buy it!!) its off plan and think it would be a nice opportunity to use one of these, so feedback welcome on all makes as not really made my mind up on who iam going with yet.

so tell me your stories good and bad please

[thebigcheese]

what way are u planning on using it underfloor heating or rads?

[p_p]

Hi Paul

A good friend of mine has installed an ecodan, to do the rads and hot water and he is over the moon with it, they must be set up spot on though.
Give me a call and I'll give you his number so you can speak with him.

PP

[superswill]

what way are u planning on using it underfloor heating or rads?

underfloor but i am open to options

[superswill]

Hi Paul

A good friend of mine has installed an ecodan, to do the rads and hot water and he is over the moon with it, they must be set up spot on though.
Give me a call and I'll give you his number so you can speak with him.

PP

thankx pp, will do

hope the snow has cleared

[thebigcheese]

yea mate there good when there sized correctly and set up well

have seen 2 units nearly running 24hours a day to keep the temp up also bringing on heaters on the buffer tank each time it was on defrost...... which in december was about every 20 mins so you can imagen the elec bill
(this was sized and set up by a plumber... first time hed done it)

not to put you off tho just make sure its done right and you will be fine

[mad fridgie]

The simple trick with underfloor heating and a heat pump, is to have a high flow of water going through the floor, very small temperature split. temp should only be around 30C, this keeps the condensing pressure very low so power use is low, make sure the the exapsion device is sized for lower liquid pressures. (suggest EEV).
If you do not get the application right you will not get the enconomy of the heat pump right. this where most mistakes are made, its not just acase of swapping a boiler for a heat pump

[desA]

Basically, if I understand your logic correctly, MF - it is important to match the heat delivery system to the grade (temperature) of the heat being supplied.

Do you have any useful links to underfloor loop design, convective radiators?

[DEVIL]

Basically, if I understand your logic correctly, MF - it is important to match the heat delivery system to the grade (temperature) of the heat being supplied.


Yes you are correct, but what MF also waned to say was that if you go with underfloor u have the water below of 40 deg C (wen is very cold outside) and if you go for rads you probably have above 50, and the difference is in the detriment of the COP that the heat pump is having up to 30% depeinding on the Heat Pump, for the same load, and that means 30% more electricity.

superswill
Wat i would recommend would be a Zubadan unit, because it holds it's Power production the same up to -15 deg C and at a good COP, and if u see the runtime until defrost its astonishing, and a shorter time for defrost.
And most important NO NEED for a backup heater

[back2space]

Superswill check out money saving expert forums there is some topics in discussing in the heating forums regarding heat pumps with many people who have installed these and posted their findings for underfloor heating or radiator methods.

[mad fridgie]

Yes you are correct, but what MF also waned to say was that if you go with underfloor u have the water below of 40 deg C (wen is very cold outside) and if you go for rads you probably have above 50, and the difference is in the detriment of the COP that the heat pump is having up to 30% depeinding on the Heat Pump, for the same load, and that means 30% more electricity.

superswill
Wat i would recommend would be a Zubadan unit, because it holds it's Power production the same up to -15 deg C and at a good COP, and if u see the runtime until defrost its astonishing, and a shorter time for defrost.
And most important NO NEED for a backup heater
I am sure superswill, choose underfloor, as a new build I would not choose a rad system, unless you have a decent backup.
You need to care when looking at sales bulls**t,
refigeration fundementals do not allow for the same power output and good COP for a single rotation of a compressor.
So the Zubadan, must be an inverter running at low speed at some sort of higher ambient spec to give a nominal KW output, then speed up at lower ambient, If SCT is keep constant, which you will need to ensure sufficient energy at the right temperature for house heating, then the COP will plumet (drop)
The only other way to keep performance up (output) and COP high is to have 2 compressors in a 2 stage format for lower ambients, then converting to a single stage at higher ambients, and i very mich doubt this is happening. But always nice to be proved wrong.

[Karl Hofmann]

Oops Double post....:o

[Karl Hofmann]

Underfloor every time with a heat pump. It is more suited to the lower water temperatures that a heat pump produces... You can have radiators, but they would have to be huge to give the required heat output, UF gives a more even temperature throughout the day. I believe that the heat pump should be sized to run as near constantly as possible so slightly undersized is best.. Back up heating would be best provided by a conventional gas fired boiler than by electric, it isn't difficult to put in a boiler to fire up when the system would ordinarily fire up the electric elements..

[DEVIL]

mad fridgie

Yes and no

I placed the catalog on this link
http://www.fidelitas.ro/refrigeration-engineer/All%20Guide%202007-2008.pdf
on page 13 you can find the explication

and to bet back to the yes/no statement
it's like a 2 stage but one compressor (of course it's not exactly the 2 stage principle ).

in any case the COP going down, but as down as it gets it's still better then an electrical heater that has the COP of 1.

I installed one at my office (to replace a DAIKIN :)) ) and it works like a charm

[mad fridgie]

mad fridgie

Yes and no

I placed the catalog on this link
http://www.fidelitas.ro/refrigeration-engineer/All%20Guide%202007-2008.pdf
on page 13 you can find the explication

and to bet back to the yes/no statement
it's like a 2 stage but one compressor (of course it's not exactly the 2 stage principle ).

in any case the COP going down, but as down as it gets it's still better then an electrical heater that has the COP of 1.

I installed one at my office (to replace a DAIKIN :)) ) and it works like a charm
Thanks Devil:D

[DEVIL]

you are welcome , and i am here to help :)

[mad fridgie]

I have had a look a Zubadan.
Firstly we can see that they are liquid sub-cooling, this will help the evap (reducing pressure drop and increaseing evap LMTD) reducing the split between the ambient and SST.
This is a plus.
The vapour injection (which has been used for sub-cooling main liquid stream) if injected into the same part of the compression cycle as the main suction would have little effect (apart from sub-cooling benifits) therefore I suspect the vapour is injected futher down the compression cycle. Very similar method to a economiser on a screw compressor. This would allow for a greater compressor outlet mass flow, and lower discharge temps (power would increase) still better than an electric element.
Very clever!

[DEVIL]

Yes you are right the injection port is further down on the compresion cycle.
and yes it's similar to the economizer but the main difference is that the liquid receiver (called as the power receiver ) is heated up by the supercooled and before the power receiver there is an extra LEV.
This is a basic schematic of the process actually in the real unit there are more LEV's that don't show up on this drawing.
And as it's stated in that catalog about defrost, sow it in reality , it's real amassing how fast it defrosts and how clean it gets not even VRV/F s do it so fast.
My last install was a 14 Kw unit , and this is the 6'th day working non-stop at 100% (didn't reached the selected temperature yet ) and no problem at all

[superswill]

planning has been put back (again)

will update ASAP on my outcome

[DEVIL]

kip us posted :))