Heat recovery units.

[Jcloughie]

I am considering installing one of these. Looking to see if anyone has any experience.



First looked at the whole house with a unit fitted in the loft and ducted from there. The ducting would not work. So then considered a cut down version, but that still needed two 100 mm ducts through the main bedroom. Possible, but not desirable. Now looking at a single room one. Cheaper, and we only have the problem in the living room. Problem there is we don’t have a suitable outside wall to fit it, so would have to go through to the garage.

Why? You may ask.

We did not know we had a problem until I added an accessory to my heating system. It provides accurate internal and external temp eater forecasts and air quality in various ways. This is what it reads right now. The house is empty and there is a window cracked.





The advice is that normal outside CO2 should be 400 but to keep inside to less than 1000. In the evening it shoots up to 2000 and when we had friends around 2500.

Filters will not get it down. Submarine scrubbers would, but not practical. Opening a window can work. But not ideal in the cold weather. So one of these units seems to be the answer. Ventilation without draughts and little loss of heat.

Does anyone have any experience of them.


John

PS, I am aware that such a unit would brake the fire regs between house and garage. But not that bothered as we don‘t use the garage for a car.

 

[otherclive]

An interesting concept will look at it further. You are correct about submarine scrubbers as you wouldn’t want a monoethanolamine system or even a pressure or temperature swing adsorber systems. All are quite energy intensive and not designed for domestic use.

For many years the submarine level for a 90 day period MPC 90 was 1%, subsequently reduced to 0.5%. Yet medical studies did not show any reduction in life expectancy even when at 1%. Wonder what drives the current recommendations given that most homes will have ventilation through the course of the day as the occupants come and go.

 

[Jcloughie]

It is interesting, we spent years improving our house with insulation and sealing. We are still miles off a new building as there are limitations caused by poor construction practices back in the 70‘s when my house was built. Hence, the CO2 issue in newhouses is a problem and heat recovery units are getting more popular, either built in or retro fit.

I was shocked at how quickly the CO2 scale climbs mostly down to breathing. I may be getting a more realistic reading this evening as I have relocated the unit onto the other side of the room, previously it was not far from my head.

We will now try to leave one window cracked open aswell.

The CO2 is completely invisible, the atmosphere feels no different even when levels reach 2500. and this can cause drowsyness.



Carbon Dioxide Levels and Your Health

• 250 – 350 ppm + background (normal) outdoor air level
• 350- 1,000 ppm – typical level found in occupied spaces with good air exchange.
• 1,000 – 2,000 ppm – level associated with complaints of drowsiness and poor
  air.
• 2,000 – 5,000 ppm – level associated with headaches, sleepiness, and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.
• >5,000 ppm – Exposure may lead to serious oxygen deprivation symptoms

John

 

[ProfJohnL]

Certainly the use of a heat recovery units such as the ones you have illustrated will make a difference, but as you pint out they are only normally practical where the house is sealed to high degree, otherwise any benefit will be overshadowed by the air exchange through other gaps.

Its very much like the effectiveness of running a dehumidifier in a caravan, with its fixed ventilation all but negating any real benefit.

But assuming your property is sufficiently well sealed then there may be a value to using a heat recovery unit.

I do need to point out that if its exchanging between wahta are two sealed volumes such as with a garage, its only a temporary benefit, as the stale air will eventually fill the garage, and then your no better off. I suspect if you research the design principles and fitting requirement's the heat recovery units should only connect between one sealed room and a volume with good free ventilation.

My father attempted to to use a 'Heath Robinson' heat recovery concept with the attic in his house, it was only partially successful, but it did prove the concept.

 

[otherclive]

I can see why you would want it in the lounge as the description seems to offer it as replacement to existing extractor fans. It doesn’t have that high an extract rate, more aligned with bathroom, whereas kitchen fans are higher. But since it can be running continuously whereas a kitchen or bathroom fan isn’t, it will remove air over a longer period and reduce CO2 content. . But in the lounge with the doors closed levels would slowly build up despite the fan running elsewhere, unless a door was periodically opened.

Be interesting to see how your levels change during the day. Do you cook with gas or all electric?

 

[Jcloughie]

Certainly the use of a heat recovery units such as the ones you have illustrated will make a difference, but as you pint out they are only normally practical where the house is sealed to high degree, otherwise any benefit will be overshadowed by the air exchange through other gaps.

Its very much like the effectiveness of running a dehumidifier in a caravan, with its fixed ventilation all but negating any real benefit.

But assuming your property is sufficiently well sealed then there may be a value to using a heat recovery unit.

I do need to point out that if its exchanging between wahta are two sealed volumes such as with a garage, its only a temporary benefit, as the stale air will eventually fill the garage, and then your no better off. I suspect if you research the design principles and fitting requirement's the heat recovery units should only connect between one sealed room and a volume with good free ventilation.

My father attempted to to use a 'Heath Robinson' heat recovery concept with the attic in his house, it was only partially successful, but it did prove the concept.

Yes, it’s designed for use to the outdoors, but the garage has plenty of ventilation around the up and over door, I think it will suffice. These units work gently over time.

John

 

[Jcloughie]

I can see why you would want it in the lounge as the description seems to offer it as replacement to existing extractor fans. It doesn’t have that high an extract rate, more aligned with bathroom, whereas kitchen fans are higher. But since it can be running continuously whereas a kitchen or bathroom fan isn’t, it will remove air over a longer period and reduce CO2 content. . But in the lounge with the doors closed levels would slowly build up despite the fan running elsewhere, unless a door was periodically opened.

Be interesting to see how your levels change during the day. Do you cook with gas or all electric?

We cook with electric. I don’t suspect there is an issue in other rooms as the kitchen is doorlessly linked to the conservatory so a large volume of air.

I will move the unit around the house. But I feel sure the real problem is living room.

So far it has encouraged us to leave a window cracked open, and this may be enough. and the problem will subside the warmer it gets. I may defer getting a unit until next winter starts.

Out of interest, I believe the units work with Radon also, but we don’t live in a Radon area.

We will probably have had high levels for years especially when there were four living here. But were not aware and it never seemed to cause a problem. We live similar to other people so I imagine many are over the recommended limits.

John

 

[otherclive]

We cook with electric. I don’t suspect there is an issue in other rooms as the kitchen is doorlessly linked to the conservatory so a large volume of air.

I will move the unit around the house. But I feel sure the real problem is living room.

So far it has encouraged us to leave a window cracked open, and this may be enough. and the problem will subside the warmer it gets. I may defer getting a unit until next winter starts.

Out of interest, I believe the units work with Radon also, but we don’t live in a Radon area.

We will probably have had high levels for years especially when there were four living here. But were not aware and it never seemed to cause a problem. We live similar to other people so I imagine many are over the recommended limits.

John

There are only limited sources of carbon dioxide in a house so the fact that you cook by electric would reduce that aspect. Humans exhale about 4 % carbon dioxide in breathing which is 100 times the normal atmospheric level, so in a closed room with limited ventilation levels will build up, particularly if people are sitting for say 3-4 hours, but much depends on room volume and any free ventilation in the levels attained. Plants also release carbon dioxide at night too. An office developer couldn’t figure out the variable co2 levels which were higher in winter mornings; plants were the cause 🌳🌴. Bin the palm trees. LOL

 

[Jcloughie]

There are only limited sources of carbon dioxide in a house so the fact that you cook by electric would reduce that aspect. Humans exhale about 4 % carbon dioxide in breathing which is 100 times the normal atmospheric level, so in a closed room with limited ventilation levels will build up, particularly if people are sitting for say 3-4 hours, but much depends on room volume and any free ventilation in the levels attained. Plants also release carbon dioxide at night too. An office developer couldn’t figure out the variable co2 levels which were higher in winter mornings; plants were the cause 🌳🌴. Bin the palm trees. LOL

A stat in this link says.

and more than 1 million kg of CO2 is emitted every second worldwide, due in large part to the use of fossil fuels (oil, natural gas and coal).

Although it is Netatmo units I am using I only just found that link and it is an interesting one.

And if you are interested this link at chapter 13 explains what my unit does in this respect.

John

 

[ProfJohnL]

I would be a little cautious about the content of both of those documents, they are both produced by the manufacturer of the product, and will of course be emphasising points that will encourage you to purchase their equipment. They also blur the distinction between global warming and climate change, they are not always the same thing.

But if you do spend time in a sealed environment, there is a real need for proper ventilation process.

 

[Jcloughie]

I would be a little cautious about the content of both of those documents, they are both produced by the manufacturer of the product, and will of course be emphasising points that will encourage you to purchase their equipment. They also blur the distinction between global warming and climate change, they are not always the same thing.

But if you do spend time in a sealed environment, there is a real need for proper ventilation process.

Possibly, but the docs are not part of their advertising and the second only available after purchase. They may though have a different slant than we are used to as they are a French company and they will be translations.

I don’t think they manufacture ventilation products, but monitoring and smart control systems. I have used their smart rad stats and thermostats for 4 years now, the are well made, reliable and very well supported. This gives me confidence.

The results from the weather station can be shared, others can see my outside only data, and I can see theirs. From this I can see they sell pretty much worldwide, But not North America.

The numbers are temperature just now.





John

 

[Sam Vimes]

Apologies for late reply and formatting. I'm doing this on smartphone with dodgy internet

• Personally I’m a bit sceptical about this type of unit but probably because I’m biased having a whole house MVHR.
• There are some things i would consider first before going ahead with one of these.
• The unit is small and the outside intake and exhaust are close together. This may result in the exhaust air being sucked back into the intake. A similar problem may exist on the room side, preventing the air in the room being exchanged fully.
• This leads to the actual air flow rate. At the time we installed ours Scottish regs called for 2.5 air changes per hour for the whole house. You should look at the volume of your room and this units flow rate and see what you’d acheive. Obviously you don’t need to comply fully with the regs.
• The unit supposedly produces a negative pressure in the room to encourage air from other rooms flowing into it. This will only work if you have open doors or there are sufficient gaps under the door.
• This may also lead to draughts if you have other sources of air leaks e.g. trickle vents.
• The efficiency is not very high in comparison with our unit. 78% compared with ours which is over 92%. This difference needs to be made up from your heat source.
• Low temperatures can effect or even damage the actual heat exchanger element so look carefully at its operating temperature range.
• Also we are amazed at the amount of dust and dirt that the filters collect and I don’t think this unit has any.
• Also condensation can build up on the heat exchanger affecting performance and has to be dealt with...how? Ours has a condensate drain

 

[otherclive]

Apologies for late reply and formatting. I'm doing this on smartphone with dodgy internet

• Personally I’m a bit sceptical about this type of unit but probably because I’m biased having a whole house MVHR.
• There are some things i would consider first before going ahead with one of these.
• The unit is small and the outside intake and exhaust are close together. This may result in the exhaust air being sucked back into the intake. A similar problem may exist on the room side, preventing the air in the room being exchanged fully.
• This leads to the actual air flow rate. At the time we installed ours Scottish regs called for 2.5 air changes per hour for the whole house. You should look at the volume of your room and this units flow rate and see what you’d acheive. Obviously you don’t need to comply fully with the regs.
• The unit supposedly produces a negative pressure in the room to encourage air from other rooms flowing into it. This will only work if you have open doors or there are sufficient gaps under the door.
• This may also lead to draughts if you have other sources of air leaks e.g. trickle vents.
• The efficiency is not very high in comparison with our unit. 78% compared with ours which is over 92%. This difference needs to be made up from your heat source.
• Low temperatures can effect or even damage the actual heat exchanger element so look carefully at its operating temperature range.
• Also we are amazed at the amount of dust and dirt that the filters collect and I don’t think this unit has any.
• Also condensation can build up on the heat exchanger affecting performance and has to be dealt with...how? Ours has a condensate drain

The unit under consideration is on a par with a bathroom fan and I’m sceptical that it would make much difference to a lounge even running continuously as during the day doors and movement tend to open up the house.

 

[Sam Vimes]

I admit that my first thought was that it's a hyped up extractor fan but with no personal experience of these units I could be wrong

 

[Jcloughie]

Apologies for late reply and formatting. I'm doing this on smartphone with dodgy internet

• Personally I’m a bit sceptical about this type of unit but probably because I’m biased having a whole house MVHR.
• There are some things i would consider first before going ahead with one of these.
• The unit is small and the outside intake and exhaust are close together. This may result in the exhaust air being sucked back into the intake. A similar problem may exist on the room side, preventing the air in the room being exchanged fully.
• This leads to the actual air flow rate. At the time we installed ours Scottish regs called for 2.5 air changes per hour for the whole house. You should look at the volume of your room and this units flow rate and see what you’d acheive. Obviously you don’t need to comply fully with the regs.
• The unit supposedly produces a negative pressure in the room to encourage air from other rooms flowing into it. This will only work if you have open doors or there are sufficient gaps under the door.
• This may also lead to draughts if you have other sources of air leaks e.g. trickle vents.
• The efficiency is not very high in comparison with our unit. 78% compared with ours which is over 92%. This difference needs to be made up from your heat source.
• Low temperatures can effect or even damage the actual heat exchanger element so look carefully at its operating temperature range.
• Also we are amazed at the amount of dust and dirt that the filters collect and I don’t think this unit has any.
• Also condensation can build up on the heat exchanger affecting performance and has to be dealt with...how? Ours has a condensate drain

Very detailed and informative reply, thank you. A whole house MVHR is out of the question to retro fit. I thought of a cut down version which extracted from the kitchen and upstairs bathroom. And feeds back to the main bed and living room. Downsides are passing two 150mm pipes through the bedroom (which we hope to re furnish this year). Other downside is persuading the wife.

I do see the benefits. the single room idea is just an easy option. We tried to imagine how it would look on the living room wall, and are put off.

So far, just cracking a window makes a big difference. Evenings we read about 1200 ppm so much improved on previous.

The unit under consideration is on a par with a bathroom fan and I’m sceptical that it would make much difference to a lounge even running continuously as during the day doors and movement tend to open up the house.

I think it is far less powerful than an extractor fan. But designed to be in used continually, and to replace what is extracted. We have extractors in the downstairs loo, the bathroom and a cooker hood. A couple of years ago I fitted non return valve to all of them which has helped keep heat (and CO2) in.

John

 

[otherclive]

Very detailed and informative reply, thank you. A whole house MVHR is out of the question to retro fit. I thought of a cut down version which extracted from the kitchen and upstairs bathroom. And feeds back to the main bed and living room. Downsides are passing two 150mm pipes through the bedroom (which we hope to re furnish this year). Other downside is persuading the wife.

I do see the benefits. the single room idea is just an easy option. We tried to imagine how it would look on the living room wall, and are put off.

So far, just cracking a window makes a big difference. Evenings we read about 1200 ppm so much improved on previous.



I think it is far less powerful than an extractor fan. But designed to be in used continually, and to replace what is extracted. We have extractors in the downstairs loo, the bathroom and a cooker hood. A couple of years ago I fitted non return valve to all of them which has helped keep heat (and CO2) in.

John

At 1200 ppm there’s not a lot to worry about. I know it’s less powerful than a kitchen extractor, ours is 250 m3 per hour. But the Xpelair shown is more akin to a bathroom one, although you can get more powerful units for bathrooms. I just don’t see it being that effective for getting lounge levels down, as during the day normal activities sees doors opened and wider mixing throughout the home. External doors give further mixing. So whilst it will be removing some “ stale” air it’s probably trying to reduce it throughout the house, until you settle in for the evening within the lounge. Then it depends on the volume of the lounge to assess air changes per hour, but you will be bringing air into the lounge from within the home albeit with a possibly lower CO2 level.

I fitted one of these to our daughters extractor when the kitchen was upgraded. It stopped tge cold back draught. Effective in its prime purpose but doesn’t help CO2 or stale air removal.

 

[Jcloughie]

At 1200 ppm there’s not a lot to worry about. I know it’s less powerful than a kitchen extractor, ours is 250 m3 per hour. But the Xpelair shown is more akin to a bathroom one, although you can get more powerful units for bathrooms. I just don’t see it being that effective for getting lounge levels down, as during the day normal activities sees doors opened and wider mixing throughout the home. External doors give further mixing. So whilst it will be removing some “ stale” air it’s probably trying to reduce it throughout the house, until you settle in for the evening within the lounge. Then it depends on the volume of the lounge to assess air changes per hour, but you will be bringing air into the lounge from within the home albeit with a possibly lower CO2 level.

I fitted one of these to our daughters extractor when the kitchen was upgraded. It stopped tge cold back draught. Effective in its prime purpose but doesn’t help CO2 or stale air removal.

View attachment 3108

Thats the sort of thing I put on our bathroom and cooker hood. does the job. I did try a thin floppy one but that squealed, (see pic and avoid). The downstairs loo is different. It has an iris on the ceiling side, but that iris has a delayed action. I never understood the logic of that. Is is only opening when you depart the room.



As you say 1200 not an issue. its around 850 during the day. But it is amazing how fast it come up in the evening.

As an aside, we very recently had the glass updated in our double glazing to Pilkington K. The old stuff was plain glass. The improvement is very noticeable . This morning, for example. car had ice on it. small window in lounge cracked open, but lounge was warm, radiators only warm.

John

 

[otherclive]

Thats the sort of thing I put on our bathroom and cooker hood. does the job. I did try a thin floppy one but that squealed, (see pic and avoid). The downstairs loo is different. It has an iris on the ceiling side, but that iris has a delayed action. I never understood the logic of that. Is is only opening when you depart the room.

View attachment 3109

As you say 1200 not an issue. its around 850 during the day. But it is amazing how fast it come up in the evening.

As an aside, we very recently had the glass updated in our double glazing to Pilkington K. The old stuff was plain glass. The improvement is very noticeable . This morning, for example. car had ice on it. small window in lounge cracked open, but lounge was warm, radiators only warm.

John

Given your background you may find this article in CNN of interest. The link to CO2 as a means of assessing indoor air quality is aligned with your ideas.

This invisible Covid-19 mitigation measure is finally getting the attention it deserves | CNN

With mask mandates virtually gone and vaccinaton rates at a standstill, there's one mitigation measure that can still make a big difference: ventilation.

edition.cnn.com

 

[Jcloughie]

Given your background you may find this article in CNN of interest. The link to CO2 as a means of assessing indoor air quality is aligned with your ideas.

This invisible Covid-19 mitigation measure is finally getting the attention it deserves | CNN

With mask mandates virtually gone and vaccinaton rates at a standstill, there's one mitigation measure that can still make a big difference: ventilation.

edition.cnn.com

I agree, it is an easy measurement to take which is indicative of other possible problems.

This is what it says in my instructions:

CO2 measurement
Due to the accumulation of gases from adhesives, cleaning products, smoke, dust, dust mites and mold in a con􏰀ned space, your indoor air can rapidly become unhealthy. The CO2 is produced by human activities and can rapidly concentrate in con􏰀ned spaces such as a living room, bed room, o􏰅ce... As CO2 level rises, so does the concentration of unhealthy components of indoor air. CO2 level is therefore a good air quality indicator. The CO2 level is measured by the station's indoor module.
13.2 CO2 indicator


Ikea now do a monitor for £12.

John