Airtight stove for house with HRV

fclauson

this is a big and often unaddressed problem - and you will see other posts from me asking fro MVHR "experts" of which I can find none

I am now working with a couple of UK companies

there are suggesting fire valves in both the sitting/stove room, the kitchen and if I go for an internal heat source other than a HP then in the room which contains that too (e.g. oil burner or gas)

they are also suggesting both supply and extract in the stove room for two reason
1 - so that you can (very slowly due to air volumes) spread the heat around the house
2 - create no negative or positive pressure in the stove room so that when you open the door no smoke/ash gets sucked out the fire

they are also suggesting the system is connected to the fire alarm/smoke detector system so that it shuts down in the event of the alarm being triggerd - no point in feeding the fire/smoke into your bedrooms :mad:

the CO2 detector and humidity detector in the MVHR system will/can control the speed of extract (house empty slows down / big party and lots of gossip system speeds up)

sas

sas wrote: »

Is it though?

The spec on their website for this model states
"Available with optional central air intake.(outside air)"

"Optional" suggests that it always has room vents too.

Might be worth double checking.

I can confirm having spoken to Boru that their stoves do not have a sealed combustion system option.

about2build

:eek: oh no....thats not what I was told. Then with quite a bit of emergency can anyone suggest an insert stove back boiler 3kw to room 15k to rads with a room sealed option

sas

about2build wrote: »

:eek: oh no....thats not what I was told. Then with quite a bit of emergency can anyone suggest an insert stove back boiler 3kw to room 15k to rads with a room sealed option

The assumption in general is that with an external air supply option, that's all anyone wants.

What I put to them was this:
" Is the stove manufactured in such a way that the only combustion air possible to enter the combustion process is via the 4 inch air intake pipe"

The answer was no.

I think we may all be getting a little too hung up on this entire concept. My brother in law has a reasoanbly airtight house. It could be better than reasoanble but it was never tested. He did use all the correct materials and it is cheap to heat so I'll assume it's pretty good. His stove is not room sealed and has a 4 inch external air supply. He's had no issues with smoke entering the room due to negative pressure nor has he mentioned any noticeable heat losses due to the stove. They love it in fact.

For my own home if I go with a boiler stove down the line, I will have a CO monitor located correctly near the stove. I am already connecting my HRV to the smoke alarms i.e. system shutsdown if any of them trigger.

If I don't go with a boiler stove I will likely insist on a stove with a sealed combustion system. I just haven't found any boiler stove anywhere at all that clearly is a sealed combustion system.

The internet is full of experts (me for example) which will entirely wreck your head. Sometimes you just gotta go with what makes sense for you and be vigilant for CO etc.

about2build

Since your reply I have been on to boru stoves in Tipperary and he maintained that the standard 600i does not come room sealed but on request one can be built ... for an extra cost. I agree with all your points above and a co2 monitor is a must i would have thought and yes link the mvhr to smoke alarms is what i am doing

sas

about2build wrote: »

Since your reply I have been on to boru stoves in Tipperary and he maintained that the standard 600i does not come room sealed but on request one can be built ... for an extra cost. I agree with all your points above and a co2 monitor is a must i would have thought and yes link the mvhr to smoke alarms is what i am doing

Someone from Boru rang me because I'd shown interest while in my local builders providers. They had passed on my details to him.

The guy I spoke to was potentially only a salesman. He didn't even know what I was talking about. Having said that, you've heard differently directly from them so I can't dispute that.

Good luck with it.

Tifosi

fclauson wrote: »

this is a big and often unaddressed problem - and you will see other posts from me asking fro MVHR "experts" of which I can find none

I am now working with a couple of UK companies

there are suggesting fire valves in both the sitting/stove room, the kitchen and if I go for an internal heat source other than a HP then in the room which contains that too (e.g. oil burner or gas)

they are also suggesting both supply and extract in the stove room for two reason
1 - so that you can (very slowly due to air volumes) spread the heat around the house
2 - create no negative or positive pressure in the stove room so that when you open the door no smoke/ash gets sucked out the fire

they are also suggesting the system is connected to the fire alarm/smoke detector system so that it shuts down in the event of the alarm being triggerd - no point in feeding the fire/smoke into your bedrooms :mad:

the CO2 detector and humidity detector in the MVHR system will/can control the speed of extract (house empty slows down / big party and lots of gossip system speeds up)

Just on the recommendation from the vendors are they suggesting fire or smoke dampers(values) fire dampers usually have fusible links and smoke, motorised values. Both usually required access, if a fusible link goes then you have bigger worries than just replacing the link.

about2build

Cheers sas. Ya its worth checking these things out.....the old saying measure twice cut once...:)

fclauson

Tifosi wrote: »

Just on the recommendation from the vendors are they suggesting fire or smoke dampers(values) fire dampers usually have fusible links and smoke, motorised values. Both usually required access, if a fusible link goes then you have bigger worries than just replacing the link.

I AM NOT EXPERT - THIS IS JUST ADIVCE I RECIVED

The fire valves are one shot affairs - i.e. in th event the "melt" and close then you have to get a new one - google "FIRE RATED EXTRACT VALVES FOR MVHR"

On "Room sealed" there bascally is no such stove if it has an opening door because the manufacture cannot gurentee that once installed that the ribbon seal around the door which stays in tact during normal operations.

Going back to the advice I received - I was refered to table 1 section 2.2 of Part J
Solid fuel burning A ventilation opening (or openings) with open appliance a total free area of at least 50% of the appliance throat opening area (of which at least 6500 mm2 is permanent ventilation) shall be provided. For description and dimensions of “throat”, see BS 8303: Part 1:1994).

So you need a duct which gives 6500 mm2 FREE AIR (i.e size your duct and then when you put vent a grill on the outside of the build make sure you still have the required FREE AIR measurement )

Hope that helps

isaos

Hello, Sorry for jumping in with a question only related to smells: The old 1996 Stanley oil fired boiler range we have in the old stone cottage (not air-tight!) we just bought is working fine, no CO2, 5 radiators. It has been serviced recently but there is a real bad smell of oil when the hot water has been switched on. We can't see any leaks, but the pipes go through a 4ft gable wall. Any idea of what we can do about that?
Thanks!

sas

fclauson wrote: »

I AM NOT EXPERT - THIS IS JUST ADIVCE I RECIVED

The fire valves are one shot affairs - i.e. in th event the "melt" and close then you have to get a new one - google "FIRE RATED EXTRACT VALVES FOR MVHR"

If you have your hrv connected to smoke/heat detector systems then the hrv will shutoff before these fire valves melt.

Are these an additional measure in case this doesn't happen or are there concerns with fire travelling the ductwork even if the hrv is off?

fclauson

sas wrote: »

If you have your hrv connected to smoke/heat detector systems then the hrv will shutoff before these fire valves melt.

Are these an additional measure in case this doesn't happen or are there concerns with fire travelling the ductwork even if the hrv is off?

I think so - but i depends - think of your duct work as a flue on an incinarator or BBQ - if there is any form of "draw" or "suck" through the pipe work then the smoke (and hence the heat and the fire) will spread through it - closing off that oppotunity has to be a good idea.

SAS - I know you have galv ducting - this will help as galv does not melt or burn too easy.

Just on the Galv vs PVC
Galv

• robust
• strong
• can cause "hum" as the air is spun down the duct by the twists of the duct
• harder to install
• might rust on bathroom extracts if you don't get condensation issues managed corectly

PVC

• easy to install
• generally viewed as quieter
• melts in a fire
• do you want to breath air that came through PVC for the rest of your life

muffler

isaos wrote: »

Hello, Sorry for jumping in with a question only related to smells: The old 1996 Stanley oil fired boiler range we have in the old stone cottage (not air-tight!) we just bought is working fine, no CO2, 5 radiators. It has been serviced recently but there is a real bad smell of oil when the hot water has been switched on. We can't see any leaks, but the pipes go through a 4ft gable wall. Any idea of what we can do about that?
Thanks!

isaos, You would be better off asking this in the Plumbing and Heating forum. Thanks

rodzer

Hello, we have a reasoanbly airtight house, test result 3. We did use a lot of the right materials and it is cheap to heat. Our stove may not be certified as "room sealed" but who cares? We love it, it's got an external air kit and burns for ages compared to an open fire. We don't have the fire dampers, fusable links mentioned above on our mvhr but maybe they can be retro fitted anyway? By the way, breathing air coming through PVC for the rest of my life doesn't bother me one bit.

paddym3

can a room sealed stove use a normal block built chimney. i am building a timber frame air tight house but want to use normal block chimney as easier to finish the capping externally and bit safer then having the flue any where near the timber kit

BryanF

Paddy it's all about the external air supply, then picking a stove that is actually room sealed, the choice of material you put around it is up to you. Choosing block is upto you. These stoves are still specialist items with many sales people still full of .... When it comes to 'fully' room sealed ' suitable' for Mvhr air-tight homes

sas

There is one issue I've heard of which goes a little something like this...

Basically the newer stoves are pretty efficient i.e. you lose less heat up the chimney.

The issue with this is that the flue gases need heat to rise and escape.

You need a pretty well insulated flue in this case to ensure that heat isn't lost by flue gases as they rise to outside. The worst risk with this is that you get a downdraft effect which is both dangerous from CO point of view but also damn unpleasant in the room i.e. smells.

However, I wouldn't for a second suggest a metal flue. They have limited life span, certainly vastly inferior to a good quality masonry equivalent.

In my case I bought flue liners made from pumice and the fill for around the liners is light weight agregate. The fill actually looks and feels like chocolate breakfast cereal. These are insulating and should help me avoid any issues.

However, I've no stove yet so can't comment if mine works or not.

There are masonry chimney systems that come with mineral wool type jackets to wrap around the flues which would also be good. They aren't cheap though.

paddym3

@bryanf i have a 150 mm external air supply for each stove and aware of the thernal bridge but block is finished and can with stand the heat as a flue lined system still hads cold bridge but not as much alos timber must be a min of 50mm from it so ost space any way.
must pm you

at sas
ys ihave seen the aggregate you on about it very light and hold heat well i am still toying with using standard clay lineers nad maybe a flue internal but not sure how or would it work or is it money wasted

Gasket

Hi All,
I'm new to the whole airtightness thing. I'm in the process of a new build (block construction, airtight MHRV) the floorslab is going in next week & i'm trying to figure out how to lay the air supply pipe for a future room sealed stove. One fireplace is on an outside wall but the other isn't. I'm told i need a minimum 100mm pipe to feed the stove but does anyone have any advice on how the pipe is carried up above ground level on the outside?

As far as i can see the only way will be to put a grille on the outside wall, then carry the 100m pipe down through the cavity, into the floor slab & then up in the back corner of the fireplace. Is there any issues with this, ie fire spreading to the pumped cavity insulation?

I've been told to slope the pipe & then put some holes at the lowest point, to drain off any condensate, but is it not encased in concrete?
Hopefully somebody has experienced this dilema before & can advise me?
Thanks

heavydawson

Gasket wrote: »

Hi All,
I'm new to the whole airtightness thing. I'm in the process of a new build (block construction, airtight MHRV) the floorslab is going in next week & i'm trying to figure out how to lay the air supply pipe for a future room sealed stove. One fireplace is on an outside wall but the other isn't. I'm told i need a minimum 100mm pipe to feed the stove but does anyone have any advice on how the pipe is carried up above ground level on the outside?

As far as i can see the only way will be to put a grille on the outside wall, then carry the 100m pipe down through the cavity, into the floor slab & then up in the back corner of the fireplace. Is there any issues with this, ie fire spreading to the pumped cavity insulation?

I've been told to slope the pipe & then put some holes at the lowest point, to drain off any condensate, but is it not encased in concrete?
Hopefully somebody has experienced this dilema before & can advise me?
Thanks

Hey Gasket,
I'm in a similar situation. I really don't want to break the insulation around the house by having a 4" pipe running through it, even if it's only for a short run. To that end, I'm running the pipe all the way out under the footpath, underneath the driveway, and having it emerge up through our lawn. I don't believe condensate should be an issue because you're not sending warm air through the pipe. I don't know exactly how high I'll need to bring the pipe up from the lawn (possibly 1ft), but I know I'll need a suitable cap to prevent rainfall into it, and also some sort of cowl that'll stop vermin getting in (if the height doesn't already solve it).

Because the pipe will be away from the house by about 7-10 meters, I'm not sure I need to tee it to negate the air pressure issues. It's effectively out in the open and shouldn't be subject to the compression/suction effect on varying sides of the house. I'm open to others opinions on this matter.

PeteHeat

heavydawson wrote: »

Hey Gasket,
I'm in a similar situation. I really don't want to break the insulation around the house by having a 4" pipe running through it, even if it's only for a short run. To that end, I'm running the pipe all the way out under the footpath, underneath the driveway, and having it emerge up through our lawn. I don't believe condensate should be an issue because you're not sending warm air through the pipe. I don't know exactly how high I'll need to bring the pipe up from the lawn (possibly 1ft), but I know I'll need a suitable cap to prevent rainfall into it, and also some sort of cowl that'll stop vermin getting in (if the height doesn't already solve it).

Because the pipe will be away from the house by about 7-10 meters, I'm not sure I need to tee it to negate the air pressure issues. It's effectively out in the open and shouldn't be subject to the compression/suction effect on varying sides of the house. I'm open to others opinions on this matter.

Hi,

Take a look at periscope vents Here

Personally I would much prefer to sacrifice a little air ingress than damaging the damp proof course / radon barrier.

Water will follow the pipe you describe where it enters through the screed also you must be absolutely sure that all joints are watertight and that the cap you propose is well maintained because I can't imagine anything worse than the smell of stagnant water entering the room.

Just food for thought.

.

thesteve

I know this is an old thread but did anyone find a decent airtight stove with back boiler in the end?

heavydawson

thesteve wrote: »

I know this is an old thread but did anyone find a decent airtight stove with back boiler in the end?

I found a pretty good one. Will PM you the details

BryanF

Effects wrote: »

Can you PM it to me as well please? I'm looking into the same thing.

the way this works is YOU PM the poster, there is NO Need for posts asking for PMs thank you

Effects

BryanF wrote: »

the way this works is YOU PM the poster, there is NO Need for posts asking for PMs thank you

Yeah, I get it. Cheers.

about2build

Boru 600i comes in 800i and a smaller model also.. you have to aspecify airtight

fifib

hi guys, shopping for 2 stoves for our new build airtight home with HRV and insulation is external - 8inches of it. i know normal Kw calculators for the stoves are no good to us as they dont take into account the extra insulation but i found one on UK site that you could specify if house was traditional cavity or passive style - which ours is.
based on this the cassette stove were looking for needs to be only 1-2Kw - do these even exist?
the other room is a sunroom/conservatory style room with vaulted ceiling (4.2m x 4.8m)and room has double door size opening into kitchen dining which is 8m x 4.5m - again we would only need 3-4Kw stove for this area. neither require back boiler.

we have been to our local stoves shops and were recommended the boru 600i and the Dovre 4CB or Charnwood cove 3 but our engineer has told us their way too high and if we put fire down we'd have to leave house!
can anyone tell us if its possible to get stoves as low as 1-2Kw that are room sealed?

heavydawson

fifib wrote: »

hi guys, shopping for 2 stoves for our new build airtight home with HRV and insulation is external - 8inches of it. i know normal Kw calculators for the stoves are no good to us as they dont take into account the extra insulation but i found one on UK site that you could specify if house was traditional cavity or passive style - which ours is.
based on this the cassette stove were looking for needs to be only 1-2Kw - do these even exist?
the other room is a sunroom/conservatory style room with vaulted ceiling (4.2m x 4.8m)and room has double door size opening into kitchen dining which is 8m x 4.5m - again we would only need 3-4Kw stove for this area. neither require back boiler.

we have been to our local stoves shops and were recommended the boru 600i and the Dovre 4CB or Charnwood cove 3 but our engineer has told us their way too high and if we put fire down we'd have to leave house!
can anyone tell us if its possible to get stoves as low as 1-2Kw that are room sealed?

We run an Inis Meain Mk II Boiler in our living room which is 5.2mW x 5.1mL x 2.7mH. That's a 7KW to room. We have double doors into kitchen area which is 9m x 4.8m. The stove heats them both. Living room is probably up on 25-26 degrees while the kitchen gets up to 24. It does all the downstairs rads and the hot water at the same time. I think your engineer is bang on. The 600i would be more than twice the output needed, unless you're trying to heat the kitchen too, but even with the doors open, the room the stove is in will be very hot.
So I'd be looking at 3-4kw for the room and _maybe_ up to 7 if you're going to leave the double doors open all the time
Boru do the Fiachra @ 7kw - http://borustoves.ie/shop/dry-stoves/fiachra-insert-dry-stoves/

fifib

heavydawson wrote: »

We run an Inis Meain Mk II Boiler in our living room which is 5.2mW x 5.1mL x 2.7mH. That's a 7KW to room. We have double doors into kitchen area which is 9m x 4.8m. The stove heats them both. Living room is probably up on 25-26 degrees while the kitchen gets up to 24. It does all the downstairs rads and the hot water at the same time. I think your engineer is bang on. The 600i would be more than twice the output needed, unless you're trying to heat the kitchen too, but even with the doors open, the room the stove is in will be very hot.
So I'd be looking at 3-4kw for the room and _maybe_ up to 7 if you're going to leave the double doors open all the time
Boru do the Fiachra @ 7kw - http://borustoves.ie/shop/dry-stoves/fiachra-insert-dry-stoves/

the Boru was recommended for a living room which is approx 4.5m x 5m so yea well over what we need in there. the kW calculator is showing up with 1kw for that room

the sunroom -kitchen/dining - were nto going to put doors between the two rooms, in plans we were supposed to but we prefer to leave it more open plan so I guess we'd get away with 7kw one in this space

893bet

I assume the kw output is the max output of each stove. Like any stove it can run a lot less of you feed it less and leave dampers closed.