Discussion
I installed our HRV sysytem from A-Z 4 years ago. It was a LOT of work but also very interesting and as usual, as long as you've done your research, you save a shed load of money doing it yourself and you're guaranteed a good job if your slightly handy.
The central unit is a Systemair (www.systemair.com) VR700E, a 700 M3/hour rotary recovery unit and all ductwork is spiral galvanised save for a few bits close to the central unit. This makes for easy cleaning with the right tools (I can give you the address for that also) which you can't do with the flexy crap.
My version is AC but they have since started to make a DC unit which is even more efficient so I would go for that if I were you.
You need to calculate the approximate volume of your house and average number of occupants throughout the year to decide which unit to get.
Systemair are the world leaders in HRV, I wouldn't buy anything else.
The central unit is a Systemair (www.systemair.com) VR700E, a 700 M3/hour rotary recovery unit and all ductwork is spiral galvanised save for a few bits close to the central unit. This makes for easy cleaning with the right tools (I can give you the address for that also) which you can't do with the flexy crap.
My version is AC but they have since started to make a DC unit which is even more efficient so I would go for that if I were you.
You need to calculate the approximate volume of your house and average number of occupants throughout the year to decide which unit to get.
Systemair are the world leaders in HRV, I wouldn't buy anything else.
iiyama said:
Interesting, havent come across them before.
SO what problems did you have to fit one of these? And did it cure it/them?
Well the Scandinavians (and Canadians) are the experts on HRV/ventilation, they've been doing it for years, which makes sense when you consider their climate.SO what problems did you have to fit one of these? And did it cure it/them?
No problems with the house. We did a full renovation and decided to fit HRV as it's much healthier for the occupants (fresh, EU7 filtered air) and the building structure itself when the place has good air circulation and renewal. I reckon a lot of homes would benefit from HRV but it just doesn't seem to be popular for some reason.
I imagine you have problems with damp in which case HRV will make a huge difference.
ETA Although obviously it is no substitute for fixing any underlying problems.
Edited by Driller on Friday 8th October 11:28
Driller said:
iiyama said:
Interesting, havent come across them before.
SO what problems did you have to fit one of these? And did it cure it/them?
Well the Scandinavians (and Canadians) are the experts on HRV/ventilation, they've been doing it for years, which makes sense when you consider their climate.SO what problems did you have to fit one of these? And did it cure it/them?
No problems with the house. We did a full renovation and decided to fit HRV as it's much healthier for the occupants (fresh, EU7 filtered air) and the building structure itself when the place has good air circulation and renewal. I reckon a lot of homes would benefit from HRV but it just doesn't seem to be popular for some reason.
I imagine you have problems with damp in which case HRV will make a huge difference.
ETA Although obviously it is no substitute for fixing any underlying problems.
Edited by Driller on Friday 8th October 11:28
Can hear the fan in the bathroom change note when the doors are opened and we have a woodburner, so it seems a good idea to be pumping air back into the house. Im also in the middle of building an en-suite which will need ventilation so can vent this, the bathroom and the kitchen at the same time. Not thinking about saving the planet just being practical!
Interestingly enough the Systemair HRV's dont seem to be as efficient as the Greenwood or Energivent units. Have discounted the former due to costs. £1000+VAT plus controls and ducting. The latter is £950+VAT but comes with all controls, including a humidistat. Greenwood HRV2 is rated @ 93% and the Energivent Flow @ 90%. Systemair VR400 is rated @ 80%.
iiyama said:
Driller said:
iiyama said:
Interesting, havent come across them before.
SO what problems did you have to fit one of these? And did it cure it/them?
Well the Scandinavians (and Canadians) are the experts on HRV/ventilation, they've been doing it for years, which makes sense when you consider their climate.SO what problems did you have to fit one of these? And did it cure it/them?
No problems with the house. We did a full renovation and decided to fit HRV as it's much healthier for the occupants (fresh, EU7 filtered air) and the building structure itself when the place has good air circulation and renewal. I reckon a lot of homes would benefit from HRV but it just doesn't seem to be popular for some reason.
I imagine you have problems with damp in which case HRV will make a huge difference.
ETA Although obviously it is no substitute for fixing any underlying problems.
Edited by Driller on Friday 8th October 11:28
iiyama said:
Interestingly enough the Systemair HRV's dont seem to be as efficient as the Greenwood or Energivent units. Have discounted the former due to costs. £1000+VAT plus controls and ducting. The latter is £950+VAT but comes with all controls, including a humidistat. Greenwood HRV2 is rated @ 93% and the Energivent Flow @ 90%. Systemair VR400 is rated @ 80%.
I have quickly looked at those websites and I would be very wary of the talk of efficiency etc. There is a conspicuous lack of specification info apart from the hallowed efficiency figures. Try to find these stats (amongst others) on those other sites:Parameter Value Unit
Voltage 230 V
Frequency 50 Hz
Phase 1 ~
Input power, fan motor(s) 2 x 152 W
Input power, reheater battery 1,67 kW
Input power, preheater battery 1,67 kW
Recommended fuse 10 A
Enclosure class 24 IP
Weight 48 kg
Filter, supply air EU7
Filter, extract air Aluminium
The Systemair VX400 has a 400m3/h capacity, so in one hour it will move 400m3 of air. The duct diameter on this unit is 160mm. From what I can see on the others they are 125mm or less. How much air can they move and how powerful are the motors?
The Systemair unit is made of galvanised steel, those others appear to be made out of plastic. The VX400 weighs 48KG, my VR700 weighs 70KG!
For those efficiency figures: have you ever looked at power tools like chain saws or pressure washers? The Stihl chainsaw will always have a lower claimed power output than the Black & Deckers etc but you know damn well that it's way better built. Also, I really have the impression they are much smaller/lower capacity units than the Systemair ones, so that much easier to be efficient.
An HRV system works day and night for the life of your home so it needs to able to take some stick. All the parts on the Systemair units are easily replaceable if need be-they just slide in and out.
As you can see on the site they install their products in airports and skyscrapers. I'm not sure the same can be said for the competition! They even do explosion prof fans if you have the need
This commercial unit has 4000w fans and weighs 700kg
(sorry, getting carried away)
Anyway, you'll ultimately make your own choice but after I'd looked at the Systemair website I really got the impression of solidly built, heavy duty units that will last well.
All the best with it
let us know how it goes and what you end up installing, I for one find it a very interesting topic. Edited by Driller on Friday 8th October 22:14
In a funny sort of way Im finding it quite interesting too, albeit confusing!!
Energivent Flow has 150mm ducts, (although depending on how its configured it also has 125).
Efficency rates aside I was trying to compare the Specific Fan Power figures, (or is this BS?).
Also the SAP appendix Q approved figures, (although I have no idea what this is!!)
Definatly agree about the plasticy nature of the units Ive been looking at although as far as I can tell this material is only for the casing. The systemair units do look far more industrial, (although asthetics are not even on my list of 'gotta have' you understand!!!)
Out of interest, do you know what these units do if its raining or there is high humidity outside? IS this humididty drawn into the building?
Energivent Flow has 150mm ducts, (although depending on how its configured it also has 125).
Efficency rates aside I was trying to compare the Specific Fan Power figures, (or is this BS?).
Also the SAP appendix Q approved figures, (although I have no idea what this is!!)Definatly agree about the plasticy nature of the units Ive been looking at although as far as I can tell this material is only for the casing. The systemair units do look far more industrial, (although asthetics are not even on my list of 'gotta have' you understand!!!)
Out of interest, do you know what these units do if its raining or there is high humidity outside? IS this humididty drawn into the building?
Edited by iiyama on Saturday 9th October 08:10
I've fitted a system to our house - 70's bungalow as air tight as a sieve but with a new first floor insulated over and above 2010 specs. Having the floor up helped with the ducting to downstairs!
Gradually getting there with the house - insulation under the floors, sealed under skirting, that sort of thing - it'll never ever approach a new house for air tightness but I'm doin' me best
There is a strong argument that fitting a HRV system to an old house is a waste of time - for energy efficiency I'd probably agree, but for convenience and comfort it's well worth it.
I'd recommend spiral wound steel duct (not the flexi stuff as it's not mouse-proof and is noisier apparently), DC motors as they're infinitely speed adjustable and more efficient, and boost switches by the showers - or a humidistat. Plus a summer bypass - ours automatically bypasses the heat exchanger once outside temp is over a set level, so you're not overheating an already warm house by further heating the incoming air. A control panel you can physically see is also essential - I've remote-mounted our panel from the casing to the landing wall so we can see when the filters need cleaning, extending the wiring with a length of computer type ribbon cable.
Some alledgedly more efficient units have a kind of slowly spinning heat exchanger belt-driven off a little motor, to increase efficiency. Looks very unreliable when you look inside the casing tbh - better off sticking with a heat exchanger that stays still - K.I.S.S! I'm guessing all the efficiency % ratings are a load of crap too.
Ours is a Stork unit (Starkey systems). Dead quiet in normal mode, but you can easily hear it on 100% boost (pullswitches by the showers). No condensation or mould in 4 years, no open windows in winter, no noisy fan next to your ear in the shower, and no asthma. Switch to boost, get in shower, get out and note windows are clear of steam, switch off boost and the 5 min overrun clears the room of any dampness. Genius.
Filters I wash every few months when the light comes on, I've cleaned the heat ex out maybe 4 times, and that's it for maintenance.
Point to note with the woodburner - if your house is very well sealed and you want an extract duct in the same room as the stove you may have to have an interlock if the stove doesn't have an external stove air supply, so that the HRV is locked off when the stove is on, or it may affect the draw up the flue. BCO can advise if you're feeling brave.
Cutting holes through fire resistant plasterboard ceilings and fitting the perfect ducting system to transfer smoke and fire from floor to floor means a hardwired interlinked smoke alarm system with battery backup is more than worthwhile too.
Ed to add This is our unit - made by Stork.
Gradually getting there with the house - insulation under the floors, sealed under skirting, that sort of thing - it'll never ever approach a new house for air tightness but I'm doin' me best
There is a strong argument that fitting a HRV system to an old house is a waste of time - for energy efficiency I'd probably agree, but for convenience and comfort it's well worth it.
I'd recommend spiral wound steel duct (not the flexi stuff as it's not mouse-proof and is noisier apparently), DC motors as they're infinitely speed adjustable and more efficient, and boost switches by the showers - or a humidistat. Plus a summer bypass - ours automatically bypasses the heat exchanger once outside temp is over a set level, so you're not overheating an already warm house by further heating the incoming air. A control panel you can physically see is also essential - I've remote-mounted our panel from the casing to the landing wall so we can see when the filters need cleaning, extending the wiring with a length of computer type ribbon cable.
Some alledgedly more efficient units have a kind of slowly spinning heat exchanger belt-driven off a little motor, to increase efficiency. Looks very unreliable when you look inside the casing tbh - better off sticking with a heat exchanger that stays still - K.I.S.S! I'm guessing all the efficiency % ratings are a load of crap too.
Ours is a Stork unit (Starkey systems). Dead quiet in normal mode, but you can easily hear it on 100% boost (pullswitches by the showers). No condensation or mould in 4 years, no open windows in winter, no noisy fan next to your ear in the shower, and no asthma. Switch to boost, get in shower, get out and note windows are clear of steam, switch off boost and the 5 min overrun clears the room of any dampness. Genius.
Filters I wash every few months when the light comes on, I've cleaned the heat ex out maybe 4 times, and that's it for maintenance.
Point to note with the woodburner - if your house is very well sealed and you want an extract duct in the same room as the stove you may have to have an interlock if the stove doesn't have an external stove air supply, so that the HRV is locked off when the stove is on, or it may affect the draw up the flue. BCO can advise if you're feeling brave.
Cutting holes through fire resistant plasterboard ceilings and fitting the perfect ducting system to transfer smoke and fire from floor to floor means a hardwired interlinked smoke alarm system with battery backup is more than worthwhile too.
Ed to add This is our unit - made by Stork.
Edited by andy43 on Saturday 9th October 11:18
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