Both work on similar principals - exchanging heat from moist smelly internal air to the fresh outside air as the first is expelled and the second is introduced into the house. They do this by passing them through heat exchangers.
The trickle uses 9Watts (and 21dBAs noise level) and the boost 46Watts (and 45dBAs). They can also be installed in damp bedrooms as they come with a light sensor to stop them going onto boost mode at night.
It's claims are a heat recovery up to 86%.
We are going to be putting in four. One in each of the main bathrooms and ensuites and one in the kitchen.
The whole units cost a bit more than a normal extractor fan but a mixture of the savings and importantly having a comfortable damp free house will make it a worthwhile investment.
I've estimated that the running costs of the four fans will be around £48 a year if we didn't have a PV system. With the contribution from the PV system and the fact that the boost Wattage will not be on at night I estimate it will cost us around £27 a year in electricity.
In terms of heat energy, they will of course lead to greater heat losses than a totally sealed bathroom/kitchen but the realistic would be a 0% heat recovery normal extractor fan which would lose a lot more heat. I'll calculate the heat savings over a normal extractor fan in a follow up posting when I install them.