A few weeks ago we received some great advice regarding heating and ventilation and now have another question we hope you can help with.
Our asthmatic daughter, her partner and our wee grandson are renting a very small (60m2) 2 bedroom Wellington property from us.
Our 2 main priorities are to install a system which will ventilate without pushing cold air out of the roof cavity into the flat during winter, and ensuring good air quality for our asthmatic daughter. Following advice and our own research, we had finally settled on having a balanced pressure true heat recovery ventilation system installed.
However today we were advised by a very honest ventilation salesperson that because the heat pump is too small to heat the whole property, the cold air blown in by a PPVS in winter (from the roof cavity) would be no worse than losing possibly up to 3 degrees with the heat exchanger on the balanced pressure system. He was in fact trying to down-sell us to a PPVS from their more expensive balanced pressure system.
The heat pump is currently being run only in the lounge on winter nights with the bedroom doors shut, and they use an oil heater in the baby's bedroom at night. However following advice from here they will be soon trial running the heater with all the doors open when it is easiest to heat - i.e. during the daytime, so that at night the heat pump won't have to run hard to catch up. They cannot afford much electricity.
Now we're back to wondering whether PPVS or balanced pressure?
Balanced pressure systems are more expensive, but if there won't be much benefit perhaps we would be better to look at the cheaper PPVS and put the extra money saved towards a installing a larger heat pump - however ...
Is there a substantial running cost increase from running a 3.2kw heat pump to a 5kw? If we get a larger heat pump which costs them more to run, they may not be able to afford to run it.
We're not in a position to install both a balanced pressure system and a new heat pump.
Thanks again for advice :-)