ASHP / Loft?

[dhaslam]

The heat pump was bought used and the supplier claimed that it was damaged in transit.    The main problem was that it couldn't be repaired.

[solar_cambridge]

Hi the Trianco one seems to work fine. There was a faulty relay but that was within the guarantee period so was replaced. It was installed April 2008.
A brief look on the web comes up with the 5KW unit costing  £935 so £750 is still about right for the 3kW one:
http://www.ecovisionsystems.co.uk/store/supply-only-air-source-heat-pumps/?gclid=CJqRrafiuZsCFZ0U4wod2Ca5EA

I like Trianco and have used their standard electric boilers on a couple of jobs. The chap on technical is very helpfull. I did a quote using the Activair unit after comparing the other makes on the market. I think their prices reflect the levels of marketing wages!

[StBarnabas]

Hi SolarC
my ASHP and Navitrin 40 tube system were installed by AE Solar.  They are good blokes and impressed by Trianco. I am happy with their ASHPs - so far o good..

[martin W]

Hi, looking at the specs the tranco 3.5 kw could be fitted in my loft as it will fit though the hatch.. How as life been with it so far? Any problems?

I suppose in winter if outside (loft) temp is around 5°C the unit should use around 0.75kWh and produce around 2.1kWh ish... How do the sums stack up against mains gas? I would think that mains gas and a standard boiler would work out cheaper... or does the economy 7 tarriff beat this?

Thinking on loft positioning.. I would assume the higher it could be mounted in the loft the better to utilise the solar gains from the heat in the loft. Can these be fitted on a vented store directly or must it be via a coil?

[StBarnabas]

Hi Martin
sorry have been away on holiday. Life has been essentially fine with the heat pump, but you can hear it - it sounds like an old fridge. I have no access to mains gas being in a rural location with the nearest gas supply being over 3 miles away. I pay c. 5p per unit and with say a 2.5 average COP this is about 2 p per kWh of heat. I'm not sure of mains gas prices at present. To be honest if I had mains gas I wouldn't have gone down the heat pump route.
Sean

[martin W]

I've been thinking about these again... (been working on a factory shutdown last 2 weeks (worked 160 hours over 2 weeks ) so no time to be on the forum.

anyway, my thoughts were around making some sort of green house on the front of the intake to pre heat the incoming air. Am I mad I was thinking of building the front base of said green house thingy with air bricks, then glazed front slope using an old / reclaimed double glazing unit (facing south), paint all the inside black, and mount the intake of the ASHP at the top of said greenhouse at back. My thoughts are it 'might' raise the intake temperature by 1 or 2 degrees, even with the airflow of the ASHP.

I was sort of thinking of say a 2.5ft x 4ft glazed panel........maybe bigger if I could find one.

[dhaslam]

I have at last installed the heat pump Trianco-ActivAir 5kW.  It is located in the carport outside the kitchen and it has a little shelter added  at the side to keep rain out.    It goes into the solar coil in the 850 litre buffer tank.     There was a bit of a hiccup initially.  The internal circulating pump  needed a bit of encouragement to start.

The first test was to heat the buffer tank to 40C.  This was done by setting the return to 40C and letting it cut out.     This happened in five hours.  This needed 20KWH or 4KWh per hour and the electricity needed was 6.6kw so a COP of about 3.  Outside temperature moved from 18-26C during the period.   Using it at night starting  at just under 40C it is using five KWh in four hours and it outputting a little over  2KWh.  so a COP of about 2.  Temperatures are about 8C to 12C.     I will be able to lower the output temperature later if necessary.   It actually adjusts itself by adjusting the flow to about 5C over the return.   So far solar is able to make up much of the difference in temperature.

Costs for DHW heat suppliment and some underfloor heating is  about 5KWH at 9c or 45C per day.  I won't be able to set up the underground air source for a few months so the input temperature will be go lower but I can compensate by lowering the output temperature and by using the stove on colder days

[kristen]

Interesting. We are morning bathers (sorry about that rather un-green failure to make a lifestyle change to evening showers!), and I've been thinking about a source of "instant" water heating when the store is not hot enough to make DHW during the Summer months (to avoid lighting the boiler).

Maybe a heat pump is the answer (although the temperature I'd need would possibly be the Achilles heel?).  Top up the store on E7 to that it is 60C (or somesuch, probably a lower than that would be OK as it would be guaranteed, whereas for Solar I aim for 60C so it can degrade a bit overnight)

The source water in the store is unlikely to be below 50C, does that make a heat pump to raise that to 60C possible, or is it getting an output temperature of around 60C at all that is the issue?

(I suppose pumping heat OUT of the bottom of the store and INTO the top of the store is really silly?)

[Richard Owen]

(I suppose pumping heat OUT of the bottom of the store and INTO the top of the store is really silly?)

Since you'll be closing the system, your COP will be 1 minus the losses in the heat pump.

An immersion will give you a COP of 1 with no losses and a lot fewer £s spent.

[StBarnabas]

DH
hope it goes well. My Triaco has been working fine and my simple experiments put the COP at 2-3.
Kristen, Richard is right I'm afraid - What you really need are Maxwell Daemons - shame I've been unable to find a supplier!
Sean

[EccentricAnomaly]

(I suppose pumping heat OUT of the bottom of the store and INTO the top of the store is really silly?)

No, I don't think it's silly: http://www.edavies.nildram.co.uk/2008/11/house/thermal-store.html#heat-pump

[dhaslam]

DH
hope it goes well. My Triaco has been working fine and my simple experiments put the COP at 2-3.

Thanks for your help on this.     The buffer tank I am heating doesn't  get as cold as the bottom of  of a DHW cylinder would be so it is heating warm water.   I think that I will try to run the tank colder  before starting to heat it.  I can do this by adjusting the individual room time/temperatures.   If the water is being heated is colder the COP should improve.     This time last year I was burning a bag of coal each day costing €10.50 trying to warm up the house to have the inside doors fitted so  the running cost is tiny in comparison.   

[martin W]

Still thinking of trying out a small trianco 3.5Kw ASHP in the future (Wood burner needs to go in first... I'm thinking of throwing it a bithday party,its nearly 1 and its still on that damn pallet in the front room ).

Anyway, nice to read the info on your experiments. At least its shows real world examples of Cop...

If I stick one in, its most likely go in the loft like StB's. To this end I have just stuck some one wire sensors up there and well the loft is much warmer than I would have expected  I've got just under 7°C (on three sensors in the air placed in different locations of the loft), and its -3°C outside at 18:34 pm.

Is a loft normally that warm? I have 200mm of loft insulation (400mm in around half the area and also floored ontop of that). The 172 litre thermal store is also in the loft (at 19°C at the moment), but thats got around 400-600mm of insulation all around it.

Anyway I'll what the air temp is over the next few days.. but should it be so high?

[dhaslam]

I  checked the temperature  in the area above the insulation last week on an average day.   I was only getting about 6 degrees  in the late afternoon while freezing outside.  The solar panels produced about 4kwh that day so it wasn't particularly sunny.   The insulation goes across the collar ties  so there is a  triangular space at the top.   I was thinking of dividing the  space at the top with light plastic sheeting so the  south side gets warmer  and to use the air on that side as a feed to an  external store in the summer spring and autumn.     The northern side of the roof would normally cool the air a lot, the frost stays on that side all day but the strip at the top melts.   This has been the longest cold spell in Ireland for  fifty years  so it wasn't a good year to have  an air source heat pump without pre warmed air.   Just getting the air from -5 to +5C would double the output and I hope to do a bit better than that next year.   

Using the air directly from the attic wouldn't be a  efficient because  there wouldn't be much stored heat in the air.   The temperature would drop fairly quickly, however during the summer such big collection area  should be able to produce a lot of heat for storing, I wonder if it might be sufficient as the only source for the seasonal  heat store. 

[martin W]

As for a seasonal heat store I think a loft located ASHP might be a winner.... I would think on a good summers day loft temps would be around 35-45°C. Not sure how much the ASHP would cool that though. I'm on mains gas, but summer quarter used is so low that I always pay high rate (6.5p/Kwh afaik), so a Cop of around 2 plus would save money at current lecy prices.

just looked at loft temp and its down to just above 4°C..