Topic: heat recovery system

heat recovery system 

Hi everyone

Can someone please help us with some advise.

We are in CHCH and built a house 1 1/2 years ago. We have a Fujitsu heatpump (8kw heating) in the living area which barely heats the 2 living areas. Stupidly we installed a Securimax heat transfer unit when the house was being built thinking that it would take heat from the living areas into the 3 used bedrooms. As you can imagine this works very poorly and just sends cold air into the bedrooms.

Does anyone know if there is a heat exchange unit out there that i can source and get it connected into the heat transfer unit? This would ideally use some of the heat from the heat transfer to heat the bedrooms..

NB We did over insulate the roof and walls of the house as well as installing downlights that the batts can be butted right up and no 'little chimneys' so insulation wise we are pretty right. In hindsight we should of got PVC windows installed but the cost was to much at the time....

Thanks for any suggestions guys - without being able to install a low emission log burner here in the chilly south it is very very cold.

Re: heat recovery system 

PVC windows wouldn't make much difference.
As you don't have pipes in the slab, which for all practical purposes the only way to distribute heat from one heat pump throughout a whole house, you will have to put heaters in the three bedrooms.
Oil column heaters etc, cheap to buy - expensive to run. More heat pumps, expensive to install, cheaper to run.
Heat transfer systems simply can't work with high wall heat pumps.

JK

Re: heat recovery system 

So you think R .27 windows make no difference to R.0.5 or R.7 windows. Yeah right!
You remind me of that real estate agent who thought 2 acres is the same like a hectare.
Frightening really frightening what "tradespeople" are out there.

Re: heat recovery system 

I have had a thought overnight and wondering about converting the heat transfer into a HRV type unit by turning the fan around, making a filter box and pumping air from the roof space into the main living area and 3 b/rms - at least that would help dry the house out and keep condensation down?.

Re: heat recovery system 

Hi
I'm not sure of your budget, but you could change one of the heat pumps internal units for a cartridge unit and duct of that.
Do you know what power rating your external units are rated at, the smallest ductable Fujitsu units start at 10kw.
I have the AUTA30LBLU which heats easily a 110sqm house, but they do go upto 16kw if you need more power

Here's a link to specs:

http://www.fujitsugeneral.co.nz/scripts/get-manual.pl?title=In+Ceiling+Cassette

Re: heat recovery system 

Glenn. Consider adding a thermostat to your heat transfer fan.

In the lounge, get a thermostat added to your heat transfer fan. Set the thermostat temperature to start the fan only when the lounge has been warmed. This way you warm your lounge first, then heat the bedrooms once the lounge temp has risen. This method was mentioned in an older ecobob discussion.

How to test to see if this would work? You would close all doors to the lounge area, turn the current heat transfer fan unit OFF, and see if I could get the lounge very warm via the heat pump. If you can get the room warm using the heat pump only (on a cold day), this indicates that your heat pump may have sufficient capacity. If the lounge cannot be warmed then you will be have to look at other solutions as mentioned by others.
For the thermostat, you will have to experiment to find the right trigger temperature, but the principle of operation is sound and the thermostat install cost is relatively low.

Secondly have a hard look at where you can plug any energy leaks. Can you improve your thermal drapes?

The solution above does not address fresh air ventilation, nor humidity. Perhaps you can buy a pre-loved dehumidifier for the first few years whilst your new build is drying out?
Back I in the in the day in lived in CHCH and I can appreciate how chilly it gets. Good luck.

Re: heat recovery system 

Thanks very much Mat - we have a thermostat on the heat transfer (didn't mention that) and use that currently - i might look to go in the roof space and lag the heat transfer pipes with extra batts to hopefully help with keeping the heat in.

Re: heat recovery system 

Last post should have read:
"Back in the day, I lived in CHCH... " :)

Re: heat recovery system 

Are you sure that your heatpump is working correctly?
We have friends with a new house and a single floor mounted heatpump keeps their large living area toasty warm.

Heat transfer systems are designed to transfer excess heat to cooler areas. A log burner will usually produce excess heat. The heatpump would have been sized to heat the area it is in. It wont have excess heat. In your case it sounds like it has insufficient heat.