Life after Heat Pump-Cold

lovesgshp

albyota wrote: »

Hi Geo, reading through the OP's comments, the system is actually working, as the temperature is showing 38.6C, I would hazzard a guess that the system has not been on long enough or it is being controlled incorectly (i.e. going off over night or for long periods not allowing the under floor heating to get up to store temp) or even, the heat curve is not set for the temps we have, so the installer has never set the parameters for the local area temps.

Hi Albyota
The manual is saying that the 2 indicator lights should be on. This seems to be the problem that the controller is not activated since setup. Until the OP gets back to us with more info, we are "stabbing in the dark"

Kopthat

Morning Geo and Albyota. Not sure if Goe has correct manual. Mine is SD535751 issue N, dated 03/05/10. The unit does not have a panel to the right. There is a panel below that has all the electrics and 2 circuiit breakers (1CG 1J25C/1) Re the readout panel, this has the space heating temp readout and 4 control buttons to set the heat pump temp. Also 4 buttons below, 1 red = mains lamp,
1 red = programmer live lamp, 1 green-defrost lamp, 1 yellow-fault lamp. There is also a small recessed red buton that is the manual reset switch if there is a fault on the unit and it trips out.
The unit has now been on continuosusly for two weeks. Today the temp read out from the heat pump is 43.5C. The unit is set to 55C. External temp is 4.9C.
Today underfloor working not to far off, although in cold conditions, falls. Rads are more hit and miss, and never get anyway near to required temp. Not looking forward to winter when as last yeat it got to -18C!!
Rads controlled via Honeywell CM927 and CM900 wireless thermostat. Underfloor by 3 no Heatmiser PRT/PRT-N Version 3 units.
It may be a balancing act, although installers did their best with this, it may be system design, it may be heat pump capacity.
Need someone to actually say, what you've got hear is OK, but just needs this......if life was so simple

albyota

Hi Kopthat, I have just had a look at the output temps for your system, it aint good I'm afraid, for example for 45 degree water, at 3 degrees ambient your unit drops to 10.06kW output, and at zero degrees down to 8.85kW, if, like last year, we get down minus 5 or below, your Calorex 12 kW will be a ugly garden ornament :eek:.

Here is the Calorex performance output table, see in yellow the different temperatures to output at different water flow temps. at minus 3 (45 Water) the output is a very poor 7.88kW

The table does not go as low as minus 15 like the Mitsubishi's Ecodan.

Depending on the level of insulation, size of house, (230M2..?) size/output of rads, and the way the system is controlled, you should get away with 35 degree flow through the UFH but that will probably not be hot enough for the rads.

AL

Kopthat

Al, thanks for the depressing info. So what about other heat pumps or are they all of a similar output? Maybe this explains why the RHI may not apply to domestic heat pumps, as from what I have seen, they are not now looking as good as stated.
Would a different heat pump of better design do any better. (Size of property is 230sq m, and insulation is to a high standard).
Kopthat

lovesgshp

Kopthat wrote: »

Morning Geo and Albyota. Not sure if Goe has correct manual. Mine is SD535751 issue N, dated 03/05/10. The unit does not have a panel to the right. There is a panel below that has all the electrics and 2 circuiit breakers (1CG 1J25C/1) Re the readout panel, this has the space heating temp readout and 4 control buttons to set the heat pump temp. Also 4 buttons below, 1 red = mains lamp,
1 red = programmer live lamp, 1 green-defrost lamp, 1 yellow-fault lamp. There is also a small recessed red buton that is the manual reset switch if there is a fault on the unit and it trips out.
The unit has now been on continuosusly for two weeks. Today the temp read out from the heat pump is 43.5C. The unit is set to 55C. External temp is 4.9C.
Today underfloor working not to far off, although in cold conditions, falls. Rads are more hit and miss, and never get anyway near to required temp. Not looking forward to winter when as last yeat it got to -18C!!
Rads controlled via Honeywell CM927 and CM900 wireless thermostat. Underfloor by 3 no Heatmiser PRT/PRT-N Version 3 units.
It may be a balancing act, although installers did their best with this, it may be system design, it may be heat pump capacity.
Need someone to actually say, what you've got hear is OK, but just needs this......if life was so simple

I did ask earlier. if the " programmer live" indicator was lit, but you said only the mains light. You say above there is this indicator, but not if it is illuminated.
The manual I downloaded was the H version and searching for N did not bring anything up.
Is there a buffer tank to balance the heat between the UFH and rads?
Are there bypass valves fitted to the rads?

albyota

Al, thanks for the depressing info. So what about other heat pumps or are they all of a similar output? Maybe this explains why the RHI may not apply to domestic heat pumps, as from what I have seen, they are not now looking as good as stated.
Would a different heat pump of better design do any better. (Size of property is 230sq m, and insulation is to a high standard).

Kopthat



Heat pumps are great, (I'm bound to say that though) I have a well insulated 185M2 house with UFH, and have a 8.5kW Ecodan fitted since Oct 08), (loads of info if you read my posts), The best heat pumps IMO, are Mitsubishi, Daikin, Panasonic and LG, but the most important thing is how the whole system is designed, not just the selection of the heat pump, but the heating distribution i.e. UFH and correct output rads, the only reason heat pumps are getting bad press is because they are not calculated properly (size of house, insulation levels, local weather Data or simply being installed incorrectly). However, there are over 45 manufacturers of heat pumps.......but only 4 or 5 that I would rate as useful in the UK. (and C***o'lex is NOT in my list).

I think the mistake made by the installer was by using the newbuild figure often banded around by the manufacturers of 40W/m2 x 230m2 = 9.2kW which is fine at +2 degrees, but a good design should also require that a system that can still produce the same output at minus 5 or lower, the Calorex cannot do this, if I were designing, I would have calc'd at least 50W/M2 (for newbuild) specified the 14kW Mitsubishi Ecodan or the 16kW Altherma as the output at minus 15 would still be 11kW output with 45 degree water, ASHP are the way forward, the revised MIS 3005 design v3 must be used for 100% space heating......this should kick out the cowboys....hopefully.

lovesgshp

Albyota.
I think you are being a bit harsh on the OP. We can all say which ASHP units we think are best, but that is not helping solving the problem that he has at the moment.
Think it is better to try and resolve his problem and not run the system he has down. It is probably a installer/setup issue, even though we have our own views on best units.

Kopthat

Geo, light on programmer live from what I remember has never been on, and I'm not too sure how this is activated or what it actually signifies. Certainly from the heat pump, there dosn't seem to be anything that states a switch to activate it?
I've got 4 versions of manual one version M and also version N plus two others? however, the guys who provided all the info used gerenic drawings/manuals that sometmes caused a great deal of problem as they were not sometimes related to the delivered parts. This definately led to problems with electric installation where sparky was using drawings that didn't in fact match and led to all sorts of problems that I still I not sure are totally correct. Re the rads these are Stelrad I think K3 for 'low energy system'. They are all fitted with thermostatic valves, not sure if these are the same as bypass valves.

We've got 300 litre HWT and 150L buffer tank both of which also have expansion tanks.
Seems like all the bits are here, and heat pump is working............but it's still cold.

albyota

Geo, the point I was making is that here in the UK, there is not many heat pumps that can 'cut the mustard' when our recent winter got down to minus 15 last year, and the system he/she has does not work at those temps, Kopthat's system has been mis-calculated for the application and he was asking......

"Would a different heat pump of better design do any better. (Size of property is 230sq m, and insulation is to a high standard)."

I tend not to knock other systems / installers generally, but as the MCS scheme is now even stricter than before, here in the UK, we must get a grip if heat pumps are to be incentivised, after all, people do want the lower running costs but also want to be warm when it's cold outside, and that's not what the OP has at the moment.

grahamc2003

albyota wrote: »

Hi Kopthat, I have just had a look at the output temps for your system, it aint good I'm afraid, for example for 45 degree water, at 3 degrees ambient your unit drops to 10.06kW output, and at zero degrees down to 8.85kW, if, like last year, we get down minus 5 or below, your Calorex 12 kW will be a ugly garden ornament :eek:.

Here is the Calorex performance output table, see in yellow the different temperatures to output at different water flow temps. at minus 3 (45 Water) the output is a very poor 7.88kW

AL

Al, Those performance tables really tell a story everyone buying an airtowater heat pump should exammine carefully. Although I'd expect the performance to be measured quite accurately, it has to viewed as the best performance achievable i.e. that measured in lab conditions when surrounded by the design engineers who know every nut and bolt in there.

You'd hope an actual installation would be set up to perform to those figures, but is the expertise out there (most of the time) to set a system up optimally? I expect sometimes it is, and sometimes not, with some installers sometimes out of their depth (no experience, just going by the number of poorly performing installations).

Another biggy with those performance tables, I think I'm correct that they are steady state running - i.e. no account is taken of defrosting (is that correct?). If so, of course the real performance will drop off much quicker with cooler ambient temperatures than the figures suggest. I expect defrosting is the biggest headache manufacturers have - just so easy to either waste loads of energy by either over or under defrosting.

But the good news for the op is that airtowater HPs are covered by the RHI and the interim payment (air to air isn't, neither are exhaust HPs). Just to add a little bad news to that, they are subsidising airtowater to gather more information on their performance, rather than recommending them at the moment.

If I had one performing like the OPs, I'd simply turn it off if the ambient temperature dropped to say 5C, or I saw it defrosting too often, especially if it has 12kW or so of electric heating elements inside which kick in to help the HP out sometimes. I hope he/she has other forms of room heating to use, if not, I'd install a stove or suchlike in the main room.