Flyin'Dutch' wrote:rikur_ wrote:Nick wrote:Heat pumps explained. I must say most of these points have occurred to me. I certainly won't be going down that road.
yawn....
13 minutes that could have been covered in 30 seconds.
Go on (serious question)
I can see as drawbacks
1. HIgh installation cost
2. Need for well insulated house and need for ideally underfloor heating
3. Lack of efficiency during longer cold spells
4. Need for some 'back-up' in living room/bathrooms? <-not sure about those.
My frustration is with polarised views for and against - it's actually a much more nuanced decision, and I don't think his sort of summary (or the heavy sales push for) are particularly helpful.
All he's basically said is a selection of common difficulties. The bit I do agree on is that lots of people will end-up with poorly spec'ed solutions that are not right for their need.
If you were going to do a more thorough comparison:
- existing heating & fuel type (gas CH, storage heaters, resistive electric, oil, coal, etc)
- fuel types available
- objectives (environmental, long term cost saving, short term cost saving, etc)
- status of existing installation (is it due for replacement, or plenty of life left, efficiency, etc)
- type of property and ease of retrofit
- how you use the property (are you there most of the day? most days? using all rooms, some rooms, etc)
- how well insulated is the property and extent of thermal mass
- availability of space (for hot water tank, value of freeing up space used by CH boiler, outdoor space for invertor, etc)
- any need for cooling as well as heating?
- types of air source heating (i.e. air to water vs air to air)
In our case I've got one house gas CH, and one air-to-air air-source.
The rationale for air-to-air air-source was:
- no mains gas, main alternatives were oil CH or air-to-water air-source
- objectives: long term cost saving (fuel & maintenance) and environmental benefits (and experiment with something new for personal curiosity)
- plenty of outdoor space for invertors, removing the CH boiler from the utility room removed a significant constraint on the layout
- house normally unoccupied during the day, or just one home office in use; home often unoccupied at weekends and holidays; 30% of floor space not used day-to-day;
- moderately well insulated, but not top spec.
- but nonetheless most of the year the CH was just 'taking the chill off' and rarely running full pelt (and only gets near stated efficiencies under heavy load)
- legacy CH not well suited for upgrade to wet air-source due to use of microbore pipes, small poorly placed radiators, etc. Lack of underfloor access meant upgrade would be disruptive. Conversely layout and loft access made air-to-air a relatively simple retrofit to most rooms.
- Low thermal mass meant some upstairs rooms struggled to keep cool in summer months, and would benefit from cooling
- Air-to-air gave us: individually controllable rooms; heat on demand (as opposed to continuously heating); cooling when required; most of the year it is very efficient (light load);
But on the flip side: Not cheap to install - and hence not cost effective for small rooms like toilets/store rooms; a separate solution is needed for hot water.