Heat Pumps Performace - Request Feedback on installations

• YEAR INSTALLED Commissioned early 2005
• M2 FLOOR AREA 190m2
• GROUND SOURCE ( HORIZONTAL )
• UFH D/S - winter run time 6 hr at night, two runs of 3hrs each during the day, on 24hr if really cold snap expected
• Rads upstairs rarely on
• DHW - 3 hr night time run, 40deg
• HOW WELL INSULATED WOULD YOU SAY THE BUILDING IS ? 140mm Fibreglass T/f house; suspicious of build quality though - I thinks there's gaps in the insulation some places (top and/or bottom of walls)
• COST OF INSTALLATION €10k for unit etc, €17K for rest of plumbing inc UFH etc and normal sanitary (sorry no breakdown)
• ANNUAL ESB BILL: Nov 2006 - Nov 2007 €1470 (don't know how much is HP)
• ANNUAL ESB UNIT CONSUMPTION
  2007: Day Rate: 5417 Night Rate:6711
• ARE YOU GLAD YOU USED A HEAT PUMP
  Currently not working due to a refrigerant leak or stuck TSV, and finding it hard to get a service engineer in, so probably not the best time to answer that one!
  Like: convenience, cleanliness, not reliant on fuel deliveries
  Dislike: slow dynamics, not as cheap as expected, the fact that it's broken

KAGY wrote: »

• ANNUAL ESB BILL: Nov 2006 - Nov 2007 €1470 (don't know how much is HP)
  <snip>Currently not working due to a refrigerant leak <snip>

topcatcbr wrote: »

This seem a high cost alternative to gas or oil
average esb bill €120 every 2 months x 6 = €720
1470 - 720 = 750 in 2006 would buy at least 9 months oil averaging for summer i know oil goes up in price but so does esb
assuming €250 saving ber year and cost of system over oil based system €12K very rough estimate (would welcome correction) 48 year payback.

• as i mentioned before the system was leaking so that had driven up the consumption
• I hadn't got around to changing the light bulbs (just had the ones the builder had in) my estimation of the lighting charge was about €250 p/y (lots of halogen spots (for shame! )
• People in similar size houses to mine are getting 2 fills of oil at €600 a go
• My standing rate for elec is 180+ a year (rural nightsaver) compared to €105 in cities (ordinary urban)

KCross wrote: »

[QUOTE
A HP is ideal for a low energy build as it works out itself how much heat to add and augmenting with PV means you can end up with zero running costs

fclauson wrote: »

I have the Danfoss (which is Thermia) HP

works fine - but web interface to the unit is weak and the controls for day/night are weak - this may well have changed in the past 4 years

soundskin wrote: »

YEAR INSTALLED - 2017. House is 1970s with 2 extensions
M2 FLOOR AREA - 190
RADIATORS? YES (all existing from oil system)
HOW WELL INSULATED WOULD YOU SAY THE BUILDING IS ? Poor. Tripple insulation i attic and pumped cavities
COST OF INSTALLATION 8k but installed myself
ANNUAL ESB BILL for Heat pump only €780
ARE YOU GLAD YOU USED A HEAT PUMP - Yes constant heat and hot water. No brainer

Frozen Veg wrote: »

Would a 200L hot water tank be enough for a family of 5 with an A2W system?

Would you recommend to leave hot towel rads on all the time? This causes the heat pump to never switch off, but I heard that having the heat pump cycle less is actually good.

Yes they are externally mounted - they take the "heat", including down to zero and even sub zero, from the air; it's a bit like the reverse of a fridge. They really are best used with large radiators - i.e. underfloor heating, as they typicaly run at around 25ish degrees rather than 50, 60, whatever for oil and gas. Unless you have a well insulated, and airtight house, you will basically be pumping heat into the outside world. You can get away with draughty houses with oil and gas as the rads get too hot to touch and for a short while make the room warmer; then the heat dissipates and you have to hit 'boost' again. with heatpump there's not such an option, if you open windows and let in loads of cold air, the whole house will be cold for a day or 2 until it's recovered. Which is why typically you will see MHRV (mechanical ventilation with heat recovery) which controls the air exchange, using the warm air from the house which is being exhausted, to heat the colder incoming air from outside - this way you get fresh air but are pre-heating it using the already heated air from the house to reduce the difference in temperature between inside and outside - it typically runs 24x7.

In short;

• if you have very good insulation with a good level of airtightness
• and have heat recover and not 4 inch vents in the walls
• and are prepared to either install UFH or low-temp rads

then A2W heatpump is worth a look. I've installed one 3.5 years ago in a new build, very airtight, hugely insulated, solid concrete walls internally and concrete first floor (i.e. huge thermal mass to 'soak up' heat and store it to release) and in the 3.5 years the heat pump has used 8868 kWh, mostly (>95%) at night rate, so circa 220 euro a year for heating and hot water.

You're welcome;MHRV is common in most new builds now, but its usually designed into the fabric of the building rather than being an add-on - you need ducting etc in every room. A friend of mine got it added to an extension/remodel of a house, but it was done while the house was gutted. You're not foregoing fresh air - you've a continuous feed of fresh air - the difference is it's not COLD fresh air and it is not dependent on the windiness or calmness either - it's a constant recirculation of air 24x7, but as I said it's usually in the initial build.