As I wait for the nice man from Fujitsu to appear and repair our heat pump, it would be a good idea to give you my thoughts on heat pumps. (reliability of the unit aside)
The things that the manufactures don't explain fully is "with air-source heat pump systems, it is not generally a good idea to size an heat pump (
EES) to provide all of the heat required by a house. For maximum cost-effectiveness, an
EES should be sized to meet 60 to 70 percent of the total maximum "demand load" (the total space heating )The occasional peak heating load during severe weather conditions can be met by a supplementary heating system. A system sized in this way will in fact supply about 95 percent of the total energy used for space heating".
(reference Canadian govt)Note: these numbers are arrived at under a
perfect lab test environment and as far as I can figure over a whole year, so it's another game of playing with figures.
In the real world this figure covers days when its warmer and days when its colder so if you have 2 weeks with cold temperatures, a time when you really need heat, the pump cannot met your needs.
We put this system in as a test in our office studio area, if it didn't meet our requirements we would not have to 'live' with it in the future.
Would we put another system in the house?, we may, but it would not be a air system but a underground loop system that takes the heat from the ground ( usually the ground temp only changes by a few degrees during the year, so system works more with more consistency and effectiveness)
Recommendations:
- make sure you get a written commitment from your supplier on the repair response times,
- who you can turn to if you need to escalate the call out, if the service agent doesn't perform.
- make sure the warranty/guarantee covers transfer of service agent (servicing and change of ownership) 'we still having problems in this area'