Heat Air recirculation systems
Discussion
Depends what system you're going for, but standard MHRV (Mechanical Heat Recovery Ventilation) systems expect you have an airtight house to work efficiently. That means no trickle vents on your windows, no air bricks, no dot and dab plasterboard (amazing how much air gets behind them), sealed floorboards and so on. Even solid looking brickwork lets through a surprising amount of air.
Typical modern houses loose about a third of their heat through air leakage - so a third of your bills is literally blowing away with the wind. MHRV aims to reduce it and can be over 90% efficient. The unit replaces the need for natural air circulation so you can bung up all the holes that a house normally has. Obviously that means you have to make sure the system is properly designed and installed.
Besides saving on your bills, there are reports that the systems pretty much eliminate condensation and that the filtered air is much cleaner and there is less dust in the house. The downside is that you need to clean the filters and check the unit on an annual basis.
We're going for a Vortice system in our house, but there are plenty of alternatives.
There are official ratings for systems - efficiency, power requirement and noise. The main unit is about half the size of an under worktop fridge. Ducting requires good space to fit in. Expect around 1K for the unit, then 1-2K for the ducting. It's a DIY job to fit, but you can pay the supplier about 2K or so for them to fit it properly.
Typical modern houses loose about a third of their heat through air leakage - so a third of your bills is literally blowing away with the wind. MHRV aims to reduce it and can be over 90% efficient. The unit replaces the need for natural air circulation so you can bung up all the holes that a house normally has. Obviously that means you have to make sure the system is properly designed and installed.
Besides saving on your bills, there are reports that the systems pretty much eliminate condensation and that the filtered air is much cleaner and there is less dust in the house. The downside is that you need to clean the filters and check the unit on an annual basis.
We're going for a Vortice system in our house, but there are plenty of alternatives.
There are official ratings for systems - efficiency, power requirement and noise. The main unit is about half the size of an under worktop fridge. Ducting requires good space to fit in. Expect around 1K for the unit, then 1-2K for the ducting. It's a DIY job to fit, but you can pay the supplier about 2K or so for them to fit it properly.
Edited by Tuna on Tuesday 4th August 12:11
Isn't MHRV going to be required to meet the Passive House spec in 2016?
I know a colleague from Finland was over here recently and was astonished that our houses don't have MHRV already. It seems a no-brainer to me, but then my wife is a fresh air fiend and I'm fighting a losing battle trying to keep our house warm.
They're also very good for keeping houses dry, apparently. I would think about getting a system that could have cooling added reasonably simply, if it's needed.
I know a colleague from Finland was over here recently and was astonished that our houses don't have MHRV already. It seems a no-brainer to me, but then my wife is a fresh air fiend and I'm fighting a losing battle trying to keep our house warm.
They're also very good for keeping houses dry, apparently. I would think about getting a system that could have cooling added reasonably simply, if it's needed.
MVHR here too - highly recommended. Even in a mostly-30 year old house, where you'd think it'd be pointless due to lack of airtightness it's ace. No open windows, no draughts, no condensation - a steam free bathroom mirror, clean fresh air everywhere. Zero mould/smells/mustiness.
Daughter and me had asthma - not now.
Stork main unit as above - pretty quiet unless on boost (during showers).
I fitted it as we had all the floors up upstairs - a steep learning curve but not difficult.
In a new build it's a no-brainer, and soon you won't have any choice once building regs move towards ze germans standards.
Daughter and me had asthma - not now.
Stork main unit as above - pretty quiet unless on boost (during showers).
I fitted it as we had all the floors up upstairs - a steep learning curve but not difficult.
In a new build it's a no-brainer, and soon you won't have any choice once building regs move towards ze germans standards.
Agree, one of the best invetions going. You're almost getting something for nothing. As stated above, works best with an airtight building and is indeed one of the corner stones of the pasivhaus concept.
You can even duct the inlet pipework underground for a ground source effect to make it even better.
You can even duct the inlet pipework underground for a ground source effect to make it even better.
I fitted ours - 2 storey house, while the first floor boards were all up, and new stud walls were being put in. That meant I could duct all the existing downstairs rooms from the first floor void running between the joists, and plan the whole first floor ducting before any walls went in.
Hardest part? Apart from getting the main inlet and outlet from the unit in the loft out to the soffit, it was probably the planning and figuring it all out - but the supplier did come out, survey the house, and design a ducting system with the right sized inlets/outlets/ducts.
£2k in total, 7 supply, 5 extract terminals - but if I did it again I'd design the layout and source all the bits myself - the main units come up on ebay occasionally.
Ours is steel spiral wound rigid round ducting (eg the pipework you see on the ceilings in B&Q warehouses etc), and insulated flexible foil/wire ducting for running thru the uninsulated areas eg loft. Angle grinder to cut it, lots of sparks, big boys toys
I'd also keep with rigid ducting in either plastic or metal wherever possible as it's supposed to be quieter than flexible duct. Must-haves - timed boost switches or steam sensors near showers, a bypass for warm weather, and a main unit you can actually access to change the filters. Works well.
Hardest part? Apart from getting the main inlet and outlet from the unit in the loft out to the soffit, it was probably the planning and figuring it all out - but the supplier did come out, survey the house, and design a ducting system with the right sized inlets/outlets/ducts.
£2k in total, 7 supply, 5 extract terminals - but if I did it again I'd design the layout and source all the bits myself - the main units come up on ebay occasionally.
Ours is steel spiral wound rigid round ducting (eg the pipework you see on the ceilings in B&Q warehouses etc), and insulated flexible foil/wire ducting for running thru the uninsulated areas eg loft. Angle grinder to cut it, lots of sparks, big boys toys
I'd also keep with rigid ducting in either plastic or metal wherever possible as it's supposed to be quieter than flexible duct. Must-haves - timed boost switches or steam sensors near showers, a bypass for warm weather, and a main unit you can actually access to change the filters. Works well.
andy43 said:
I fitted ours - 2 storey house, while the first floor boards were all up, and new stud walls were being put in. That meant I could duct all the existing downstairs rooms from the first floor void running between the joists, and plan the whole first floor ducting before any walls went in.
Hardest part? Apart from getting the main inlet and outlet from the unit in the loft out to the soffit, it was probably the planning and figuring it all out - but the supplier did come out, survey the house, and design a ducting system with the right sized inlets/outlets/ducts.
£2k in total, 7 supply, 5 extract terminals - but if I did it again I'd design the layout and source all the bits myself - the main units come up on ebay occasionally.
Ours is steel spiral wound rigid round ducting (eg the pipework you see on the ceilings in B&Q warehouses etc), and insulated flexible foil/wire ducting for running thru the uninsulated areas eg loft. Angle grinder to cut it, lots of sparks, big boys toys
I'd also keep with rigid ducting in either plastic or metal wherever possible as it's supposed to be quieter than flexible duct. Must-haves - timed boost switches or steam sensors near showers, a bypass for warm weather, and a main unit you can actually access to change the filters. Works well.
That is very encouraging! Do you mind me asking which unit you fitted, and supplier did the design?Hardest part? Apart from getting the main inlet and outlet from the unit in the loft out to the soffit, it was probably the planning and figuring it all out - but the supplier did come out, survey the house, and design a ducting system with the right sized inlets/outlets/ducts.
£2k in total, 7 supply, 5 extract terminals - but if I did it again I'd design the layout and source all the bits myself - the main units come up on ebay occasionally.
Ours is steel spiral wound rigid round ducting (eg the pipework you see on the ceilings in B&Q warehouses etc), and insulated flexible foil/wire ducting for running thru the uninsulated areas eg loft. Angle grinder to cut it, lots of sparks, big boys toys
I'd also keep with rigid ducting in either plastic or metal wherever possible as it's supposed to be quieter than flexible duct. Must-haves - timed boost switches or steam sensors near showers, a bypass for warm weather, and a main unit you can actually access to change the filters. Works well.
I used Starkey Systems after going to the Homebuilding show at the NEC 
The main unit is this - with DC motors (cheaper to run, infinitely variable speeds), and it's got a bypass around the heat exchanger, so incoming summer air isn't warmed further by the air leaving the building.
It's well built and designed - some are just cheap plastic glued together, not sure on it's relative purchase cost or efficiency tho'.
I've probably invalidated any warranty by remotely mounted the control panel with a length of maplin ribbon cable and plug - otherwise you can't tell when the filters need doing. And you've got to have a weird-looking control panel on the landing wall
Been installed maybe 2.5 years, banged filters out about 3 times, replaced them once.
The main unit is this - with DC motors (cheaper to run, infinitely variable speeds), and it's got a bypass around the heat exchanger, so incoming summer air isn't warmed further by the air leaving the building.
It's well built and designed - some are just cheap plastic glued together, not sure on it's relative purchase cost or efficiency tho'.
I've probably invalidated any warranty by remotely mounted the control panel with a length of maplin ribbon cable and plug - otherwise you can't tell when the filters need doing. And you've got to have a weird-looking control panel on the landing wall
Been installed maybe 2.5 years, banged filters out about 3 times, replaced them once.
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff