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Domestic Heat recovery systems

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Domestic Heat recovery systems

Postby Charlie » 09 Jan 2015, 22:17

In order to preserve Mike's thread. I've moved Charlies perfectly acceptable enquiry here for further discussion by all.
Bob


the ventilation will be via a MVHR (mechanical ventilation with heat recovery) system, which is a simple fan-in-a-box in the loft, with ducts to every room, drawing stale air out and putting fresh air in, continuously, day and night. The difference is that a heat exchanger captures almost all of the heat in the outgoing air, and warms up the incoming air with it. No smells, no mould, no condensation.......ever, anywhere. Climb out of a long hot shower in the middle of winter and you can shave in the mirror straight away without wiping it with a towel. Utterly brilliant bits of kit.[/quote]


Sorry to hijack your fantastic thread, just wondering if it is possible to retrofit this system to an existing building? My house is cob and condensation is an issue.
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Re: Domestic Heat recovery systems

Postby 9fingers » 09 Jan 2015, 22:47

Dick Strawbridge did something on retro fitting a heat recovery system in his going green series.

If you google for Dick Stawbridge and heat recovery you will find links to it.

Condensation problems can be a mix of lack of ventilation and lifestyle issues exacerbated by additional insulation.
Cooking without an external extractor and no lids on pans is on culprit.
Another is drying clothes indoors as are showers with windows closed and especially running a bath with the hot water going in first (less steam if you put cold in first)
Ideally open a window towards the end of your ablutions - not all family members will agree!!

HTH

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Re: Domestic Heat recovery systems

Postby Mike G » 09 Jan 2015, 23:03

Charlie wrote:In order to preserve Mike's thread. I've moved Charlies perfectly acceptable enquiry here for further discussion by all.
Bob


the ventilation will be via a MVHR (mechanical ventilation with heat recovery) system, which is a simple fan-in-a-box in the loft, with ducts to every room, drawing stale air out and putting fresh air in, continuously, day and night. The difference is that a heat exchanger captures almost all of the heat in the outgoing air, and warms up the incoming air with it. No smells, no mould, no condensation.......ever, anywhere. Climb out of a long hot shower in the middle of winter and you can shave in the mirror straight away without wiping it with a towel. Utterly brilliant bits of kit.



Sorry to hijack your fantastic thread, just wondering if it is possible to retrofit this system to an existing building? My house is cob and condensation is an issue.


Perfectly possible, Charlie, and it would solve your problem I'm sure. The difficulty with retro-fitting is running the ducting, so some compromise is often necessary. The upstairs rooms are typically easy, but finding 3 or 4 convenient places to drop from the loft to the ceiling of the ground floor is usually a bit of a task. Inside built-in cupboards is favourite, but sometimes it just has to be down a wall in some boxing.

There are compromise machines available, which, say, extract from the bathrooms and kitchen, but only put fresh air into, say, a hall or stairwell or whatever, and some of these can actually be located above the cooker as a cooker hood, if I remember correctly.

Have a look at the Vent Axia website, here: http://www.vent-axia.com/range/heat-recovery-and-mechanical-extract-systems

mod edit - removed the . from the URL
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Re: Domestic Heat recovery systems

Postby Charlie » 09 Jan 2015, 23:25

Thanks Mike & Bob, I'll take a look at your suggestions. Very good of you.
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Re: Domestic Heat recovery systems

Postby firedfromthecircus » 10 Jan 2015, 10:30

Good question Charlie. I was thinking the same myself as I read Mikes thread last night and was reminded again as I had my shower this morning.
So thanks again Mike for the further education. :D
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Re: Domestic Heat recovery systems

Postby Daven » 10 Jan 2015, 18:06

I bought one and fitted it into our last bungalow (there is a post on UKW) - it worked great and am thinking of doing the same here. As Mike said the ducting is the worse part (easier in a bungalow).

I wrapped the ducting in insulation and fitted a condensation trap as there was a lot of build up in the pipes. Think it cost about £1k in all in 2009.

I would be careful where it fitted it this time as the noise (albeit quiet) could be a bit annoying at night as it was sited over the bedroom which was the easiest place to put it.

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Re: Domestic Heat recovery systems

Postby Mike G » 10 Jan 2015, 19:18

Yep, good point Dave. Locate the unit itself above a bathroom, or spare bedroom, and don't put the ducts directly above a bed. The whole thing is utterly inaudible during the day, but in the night if it is incorrectly located you can just about hear a very low humming.
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Re: Domestic Heat recovery systems

Postby the bear » 11 Jan 2015, 00:33

I'm hoping to extend and renovate my place in the near future and I guess running in the pipes would be easier than for most as its a chalet bungalow. Mike, I note on your extension thread you are going to efforts to make it as airtight as possible, what happens in the old part of the house which isn't airtight as most of mine won't be?
Also what happens in summer when you want french doors and windows left open all day, is it switched off? Does having it fitted negate the need for trickle vents building regs wise? Finally does it make any significant difference to heating bills by not having to leave windows open after a shower etc in winter?

Sorry for so many questions but you have set me off thinking about how much I might benefit from one of these, having not really heard of them before.

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Re: Domestic Heat recovery systems

Postby RogerS » 11 Jan 2015, 07:58

Mike's the expert but I'll have a stab at answering.

the bear wrote:I'm hoping to extend and renovate my place in the near future and I guess running in the pipes would be easier than for most as its a chalet bungalow. Mike, I note on your extension thread you are going to efforts to make it as airtight as possible, what happens in the old part of the house which isn't airtight as most of mine won't be?


It will depend on just how un-airtight it is. If it's really leaky (as ours is) then I would suggest the heat-recovery system was pointless. In our house we have open fireplaces everywhere and we like our open fires in winter!

the bear wrote:Also what happens in summer when you want french doors and windows left open all day, is it switched off?
Good question !

the bear wrote:Does having it fitted negate the need for trickle vents building regs wise?
I'd say it does. Trickle-vents are one of those daft ideas IMO. Not every BCO bothers with them.

the bear wrote:Finally does it make any significant difference to heating bills by not having to leave windows open after a shower etc in winter?


It will depend on the answer to your first question
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Re: Domestic Heat recovery systems

Postby Mike G » 11 Jan 2015, 08:09

the bear wrote:I'm hoping to extend and renovate my place in the near future and I guess running in the pipes would be easier than for most as its a chalet bungalow. Mike, I note on your extension thread you are going to efforts to make it as airtight as possible, what happens in the old part of the house which isn't airtight as most of mine won't be?


The old part of my cottage will be completely rebuilt, and will have 4 inches of external insulation as well as 4 inches within the existing walls. Whilst lightweight, it will be airtight. In a house which isn't airtight, having a MVHR system will allow you to make it more airtight: sealing up drafts is the very best way of reducing your heating bills and increasing your comfort. If you don't get it perfect, this machine will still make a huge difference to the quality of life inside.

the bear wrote:Also what happens in summer when you want french doors and windows left open all day, is it switched off?


You turn it off. You also have a boost switch in case you burn something in the kitchen. Some of them come with a humidistat to automatically boost the speed if someone has a mega-shower, for instance, but others you just switch a boost switch manually.

the bear wrote:Does having it fitted negate the need for trickle vents building regs wise?


Yes.

the bear wrote:Finally does it make any significant difference to heating bills by not having to leave windows open after a shower etc in winter?


Yes. It is fundamental to controlling your heating bills to get control over your ventilation heat losses.
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Re: Domestic Heat recovery systems

Postby the bear » 11 Jan 2015, 19:45

This is sounding more interesting.

My early 60's chalet bungaow that I moved into 3 months ago is normal twin (brick/block) skin and solid floors throughout. So no drafts coming through the floors and I have no chimneys leaking warm air. Also pretty recent double glazing, so maybe its more airtight than I think.

As I said we are in the early days of speaking to an architect to extend and change the look of the property. I'm currently waiting on the revised drawings but we haven't got beyond talking about floor plans yet. The remodel will include a chimney for a wood burner and I believe the air for these can be fed from outside and you are doing that as well Mike? Remodel also will include insulating the cavity walls, stripping the whole roof to change the tiles and adding insulation where its missing (plenty in the eaves storage in the rafters but unsure elsewhere), changing the windows for wood but I believe these can be as good as uPVC as well.

So does it sound like I'm a reasonable candidate for one of these systems?

I'm on oil and even though the price is mega low at the moment I'm keen to keep energy build down as low as possible and this seems a reasonable outlay. It is significantly colder up the hills where I live than the surrounding valleys and weald.

Anyone got any more links to info about these systems? Also if I did this I'd do the pipe work myself, but which trade normally fits them?

Thanks

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Re: Domestic Heat recovery systems

Postby Mike G » 11 Jan 2015, 20:21

Mark, your house sounds like a perfect candidate for a MVHR system. Whilst you are doing everything else it should be very easy to fit one in.......and yes, they are a perfectly straightforward DIY job, with access being the only issue. If you are OK crawling around in your loft, you're fine to fit one of these.

You're right about having a ducted air-supply to your wood-burner. Ideal if you are buying a woodburner from scratch and can get one with an air-supply spigot, which is what I am planning to do.

Oh, and timber windows can far exceed the performance of uPVC windows.
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Re: Domestic Heat recovery systems

Postby the bear » 11 Jan 2015, 22:33

Thanks Mike and Roger.
I assume my floors are not insulated given the age of the house. Is that a problem at all. I have read that insulation and air tightness are key to getting the best out of these. I'm not aware of any way to insulate a solid floor short of digging it out and re-pouring over celotex.

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Re: Domestic Heat recovery systems

Postby RogerS » 11 Jan 2015, 22:53

the bear wrote:Thanks Mike and Roger.
I assume my floors are not insulated given the age of the house. Is that a problem at all. I have read that insulation and air tightness are key to getting the best out of these. I'm not aware of any way to insulate a solid floor short of digging it out and re-pouring over celotex.

Mark


Just a thought..how high are the ceilings? Could you not just lose x inches by laying down Celotex on what you have and then, say, a wood floor on top? Door height might be a problem in that you'd need new doors throughout, I would have thought, but depending on the height of the door frame you might get away with it?

Bit iffy maybe. I think you have to factor in how much heat will actually be lost through the floor as opposed to, say, insulating the walls and maybe fitting triple-glazed windows (which I think is what Mike is referring to as a normal timber window with double glazed units struggles to meet the new regs).
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Re: Domestic Heat recovery systems

Postby the bear » 12 Jan 2015, 00:41

Roger
Think thats a question for my architect, though we need to keep the roof height down so it might be hard. But I can only ask.
Thanks

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Re: Domestic Heat recovery systems

Postby Charlie » 14 Jan 2015, 22:04

My cob house was renovated & extended in 2009 at which time I had not heard of heat recovery systems. As far as I can remember the floor & ceiling joists run the width of the house. The house is longer than its width, so I don't know how the ducts could be run, any suggestions folks?

I suppose the loft ones could run across the top of the joists, provided I used insulated ducts.
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Re: Domestic Heat recovery systems

Postby Charlie » 17 Jan 2015, 19:17

Charlie wrote:My cob house was renovated & extended in 2009 at which time I had not heard of heat recovery systems. As far as I can remember the floor & ceiling joists run the width of the house. The house is longer than its width, so I don't know how the ducts could be run, any suggestions folks?

I suppose the loft ones could run across the top of the joists, provided I used insulated ducts.


Hi guys, any ideas for running the ducting please?
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Re: Domestic Heat recovery systems

Postby 9fingers » 17 Jan 2015, 19:26

Charlie wrote:
Charlie wrote:My cob house was renovated & extended in 2009 at which time I had not heard of heat recovery systems. As far as I can remember the floor & ceiling joists run the width of the house. The house is longer than its width, so I don't know how the ducts could be run, any suggestions folks?

I suppose the loft ones could run across the top of the joists, provided I used insulated ducts.


Hi guys, any ideas for running the ducting please?


I would assume vertical runs through the floors until you get into the loft and only then join horizontally.

Bound to be a compromise between routes through the upstairs rooms to service the downstairs rooms and minimising the "spaghetti" in the loft and avoiding the other obstacles up there.

Sounds like a job for 3D cad!

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Re: Domestic Heat recovery systems

Postby Mike G » 17 Jan 2015, 19:41

Frankly, Charlie, it is impossible to begin to advise on this without a drawing. But if you have a loft, then pipes can run anywhere in that. If above the joists & insulation, then drape some fibreglass over the ducts once you are finished. The difficulty isn't usually in the loft, so much as the vertical drops to the ground floor ceiling (if it is a 2 storey house), and horizontal runs within the first floor, which may not be possible at all.
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Re: Domestic Heat recovery systems

Postby Charlie » 18 Jan 2015, 21:45

Mike,

From memory the first floor joists run the shortest span, which I think you are saying means it's not possible to run the ducting.

However won't you have similar issues with your new build - joists running to shortest span - making duct runs impossible? However as yours is new build there may be a solution.
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Re: Domestic Heat recovery systems

Postby Mike G » 18 Jan 2015, 23:03

Charlie, I haven't said anything about the joist runs making ducting impossible. Without a drawing I have no idea what we are talking about! Essentially (ideally) you have to located vents in the furthest corner of the room away from the door, and connect them up with 4" pipes. Working from that principle, you are going to have a far better idea of what is possible or not than I ever will.....unless I visit your house or see a drawing.
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Re: Domestic Heat recovery systems

Postby Charlie » 19 Jan 2015, 18:57

Mike G wrote:Charlie, I haven't said anything about the joist runs making ducting impossible. Without a drawing I have no idea what we are talking about! Essentially (ideally) you have to located vents in the furthest corner of the room away from the door, and connect them up with 4" pipes. Working from that principle, you are going to have a far better idea of what is possible or not than I ever will.....unless I visit your house or see a drawing.


Sorry Mike, I think I must have misunderstood. From your comment above I can't put the pipes under the upstairs floor as the joists run the wrong way. I would have to have a wall mounted vertical pipe in each room to reach the loft. It's a small house so losing that much space in each room would be inconvenient. The loft is possible, but don't think doing half the house would be worthwhile.
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Re: Domestic Heat recovery systems

Postby Daven » 19 Jan 2015, 19:26

Hi Charlie,
You can get single room heat recovery extractors - Mike may know how good they are. Maybe worth the compromise and fitting to the wet rooms on first floor with a smaller system looking after the top floor.

I would recommend finding any way you can to have a system installed if your house suffers from condensation - it cut down 90% of the mould that grows around the upvc windows in our last place.

Built in wardrobes on our external walls here had mould purely down to condensation - I have just ripped them out and the walls are dry as a bone! Soon as I can afford it I will be fitting a new MHR system.

Cheers
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Re: Domestic Heat recovery systems

Postby Charlie » 24 Jan 2015, 13:42

Is there anyway of establishing which way joists are running without lifting the carpets?
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Re: Domestic Heat recovery systems

Postby RogerS » 24 Jan 2015, 13:54

Charlie wrote:Is there anyway of establishing which way joists are running without lifting the carpets?


If you had a Lumber Wizard or similar then I reckon you could scan the floor and find the nail or screw heads which might tell you the direction.
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