Chimney System - Air Tight House

Jorus

Hi,

Just wondering if anyone knows about this or if they have done it in their house?
We are building a block house - hoping to get it as air tight as possible (putting in HRV etc).

We are just wondering what is the best chimney system to put in? We are putting in a free standing log stove in one of the rooms and also a insert wood burning fire ( http://www.fondis.com/dn_the_open_hearth/) in the other room. We will need a chimney system that has an external air feed and is also air tight ?

We are looking at the Scheidel system? Does anyone else know of other systems to compare prices with?

Also the insert fire by Fondis - are they any other alternatives out there (that must be capable of connecting to an external air supply) ?


Thanks,

cormacmul

Hello Jorus,

I am interested in the same types of systems. But I am finding it very hard to get good advice. I am looking at having two solid fuel stoves. And the only advice I have been given so far is to have an extenal fuel supply so that the fires are not taking air from the house. When the fire's are not in use, then vents would be sealable.

Have you met or seen anyone that has installed the systems you are taking about, if so I would like to talk to them too.

Talk later,
Cormac

Jorus

Also - do we even need an external air source for the fire / stove if we want an airtight house with HRV?

Is it sufficent to just close the air feed vents on the front of a standard fire / stove when they are not in use?

cormacmul

Hi Jorus,

Some people I talk to, say that you don't. That the air from the HRV would be enough to feed the fire. Other people say that you need an external air source.

But to me at the moment there are to many if's and but's and no proper answers.

My understanding of fireplaces/stoves is that they are complex to get right. I would love to meet or talk to people who have fireplaces/stoves with HRV. I have talked to some HRV installers and they say they have installed them with fireplaces/stoves but when I ask for some references they arent forthcoming.

Is it sufficent to just close the air feed vents on the front of a standard fire / stove when they are not in use?

I think this would depend on the stove, but yes I think this is OK.

Please talk to some HRV installers and if you get any good specific details please let me know.

Talk later,
Cormac

CJhaughey

We have HRV and a woodburning stove (Morso Squirrel)
All last winter we burnt wood and never had any problems.
The flue height must exceed the roof of the house by a few feet or you will have downdrafts in some wind directions.
Bear in mind that the stove is quite small and we run the HRV with a slight underpressure to avoid pushing house air into the fabric of the house.

cormacmul

Hi CJ

Can you explain a bit more

we run the HRV with a slight underpressure to avoid pushing house air into the fabric of the house

If you don't push air in how can the heat be recovered from the air going out?

Talk later,
Cormac

CJhaughey

Our HRV unit Temovex 480 has 2 fan speed adjustments, one for the intake fan and one for the exhaust fan.
If you run the exhaust fan at a higher speed than the intake fan speed the house will have an underpressure.
The air still moves in and out of the house but the extract is stronger than the intake.
The heat exchange works as usual.
If you set it the reverse way there will be over pressure and moist air could possibly be forced into the fabric of the house via electrical switchplates etc.

10-10-20

Correct me if I am wrong, but a house running a negative pressure and a room-fed stove (as opposed to room sealed) will draw air back down the chimney and cause poor buring in the stove. It will also present a carbon-monoxide hazard.

True or false?

CJhaughey

Technically you are correct, In practice the fire works fine with plenty of draw and no smoke coming back down the flue. The negative pressure is only very low, and I haven't had any alarm from the CO alarm.
That said my stove is the smallest Morso make and the draw required is probably only small.
So I will say IME.
Small stove+ HRV running (slight) underpressure+ sealed house = No problems.
That may not be true for others with bigger stoves/greater draw and different HRV systems running different fan speeds.
ALWAYS have a CO alarm if you have a solid fuel stove.

cormacmul

Hi all,

I'm not very experienced with stove, does each stove have draw specifications.

If I was going to supply the stove with an external air source. Could I find out the diameter of the pipe needed by this draw specifications.

Thanks for help,
Cormac

Mellor

10-10-20 wrote: »

Correct me if I am wrong, but a house running a negative pressure and a room-fed stove (as opposed to room sealed) will draw air back down the chimney and cause poor buring in the stove. It will also present a carbon-monoxide hazard.

True or false?

In theory yes, but bare in mind that the extract will resist the under pressure also.
so it would likely make up the negitive pressure through the extract before the flue.
The under pressure is achieved by having a higher speed on the extract, the setting is fan speed not extract volume. This is key

If the pressure is equalised in the extract, that means that the resistance on the extract is equalised my the extra speed. Resulting in equal in and out and a balanced room. No air in through flue, and zero into fabric.
If then, due to athmospheric changes, the intake increases, the extract alters immediatly to cope.
Its a very good way to run in imo.

cormacmul

Hi Mellor,

So Mellor what your saying is that air is taken from the room and from the HRV extract pipe. So less air goes up these extract pipes, even tho the extract fan is running.

Thanks,
Cormac

Jorus

Just got a reply from a HRV company -

"a heating systems should have its own air source if the structure has very good levels of airtightness, If not air for outside will fill the negative pressure created by the stove."

cormacmul

Hi Jorus,

This is why I am so confused. So many different answers from different places.

If I do go with a air tight building and a HRV i will be providing access to external airsource. But the problem is here what diameter of pipe is needed to provide this air. I have been told it needs to be the same diameter as the chimney flue. I think this is 8 inches. That is a pretty big air source.

Does anyone have any comment on the above. Its a very complex area.

Thanks,
Cormac

I would be looking at "roomsealed" stoves, ones that can be attached to balanced flues or can take air from a duct.

At least then it won't have any effect on the HRV.

sydthebeat

Deleted User wrote: »

I would be looking at "roomsealed" stoves, ones that can be attached to balanced flues or can take air from a duct.

At least then it won't have any effect on the HRV.

absolutely agree with the above statement. A room sealed stove with a balanced flue or feed from a duct woul dsolve most of the issues mentioned here.

If served from a duct this duct should be piped to the external and carried through the floor to the area where the stove is located

cormacmul

Hi lads,

I can't find any information or Irish suppliers of room sealed stoves. If you can't write them here then can you PM me the details.

sydthebeat in response to

If served from a duct this duct should be piped to the external and carried through the floor to the area where the stove is located

What diameter should the duct be?

Talk later,
Cormac

10-10-20

It possibly should be the same size as the output.
The heat from the fire will cause expansion of the air, so any intake smaller than the output will possibly choke the fire.

cormacmul

Hi 10-10-20,

What do you mean by output. Is it the size of the flue?

Thanks,
Cormac

ollie30

i spoke to a co. dealing in room sealed stoves,firebox inserts etc from galway and they told me to leave a 100mm duct for most air intake ducts ,but may depend on product your buying. you'd probably need to speak to them.i'll pm you incase you dont know who i'm talking about

d o'c

ollie30 would you mind PMing me that Galway Co details also please....

timmer3

just saw this thread now, i know it's old but for anyone who's interested, i've been doing some research and got some very useful info from clearviewstoves.com on this topic.
the external air supply kit is a 3 inch stainless steel duct, which you can extend if you need to. even though the model in question (pioneer range) is advertised as room sealed, and sold with an external air supply kit as an optional accessory, when i asked for clarification on using the draught controls in conjunction with the external air supply, i got this response:

The box (external air supply kit) will only supply the secondary air outlet not the primary. So when the stove is first lit, and should you need to bring the stove back up to temperature then you will need to draw from the room.

these stoves are one of the top brands and as far as i can make out there is no completely room-sealed stove, they all take in air from the room to some degree, even with an external air supply kit. i guess once the draught control is closed as much as possible (i.e. when not in use, or overnight to keep the fire in) it's going to be pretty air-tight, at least compared to an open fire.

gman2k

Interesting...old thread reappearing..

I was in a stove supplier today (does various brands - Isle of Wight, Belgium, Chinese), and everything was going swimmingly until I mentioned that I had a MHRV in the build.
As I need a stove with a back boiler, the options seem very limited - at least with his suppliers.
There are 'snorkel' stoves available, where you feed in an external air feed, but he said he could not get any snorkel stoves with back boiler options.
He then rang his supplier as there was rumours that something was in the production pipeline. Apparently, it will be available in October (may push out to December though)

He advised fitting a 100mm dia SS duct from external to back of stove position, where this can then be connected to the stove. In my case, this will be a 100mm flexi duct, with various 90deg bends where necessary.
In most cases, this duct should be underfloor, but I've gone past this point!
I'll post back up some more information when it comes to hand, and I'll also consult with my MHRV supplier also.

timmer3

i don't need the boiler option so that gives me more options. i have a combi boiler with rads but once the stoves are in place i intend to use them and rely on the HRV to distribute the heat to the rest of the house, and hopefully not use the gas at all. i'll post back here in the winter if this idea works! i'll use the boiler for hot water anyway, and as a backup if i run out of wood or get too lazy to light up the stove. apparently wood is the cheapest fuel (although those are 2006 prices).

Wally Runs

I hope this works. I am retro fitting a 1970's home with HRV (and all the air tightness bits). We have opted for a Morso 6000 with an external air source. Please find attached the fitting information for the kit form Morso. The cost of the kit is GB£25.00.

The project is on going so I cannot say if it works as yet. The use of the kit does limit the location of the stove (external wall) unless you can go through the floor.

timmer3

i'm a few months away from buying the stoves and HRV system, i'll be watching with interest to see how well it works for you.
i'm sure you checked anyway but thought it no harm to mention that the air kit PDF doesn't mention your exact stove model "Morsø outside air kit: 3100's 3600, 7100 & 8100's"
good luck with it.

Wally Runs

Yes, saw that, have been through the hoops on this. It took us a while to convince the stove supplier that the 6000 came with an outside air kit ( because as you say it is listed againist other stoves in the range). I have been suprised how even with big suppliers you sometimes end up teaching them about their own products.

timmer3

found the same thing myself with clearview stoves, they didn't advertise the outside air kit as an accessory for the stove i wanted but to be fair the chap i spoke to was quite the expert on their products.

MacTheKnife1

I am looking for the same thing - a range and a stove that ideally should be room sealed (for the HRV).

I spoke with an Irish company recently that gave really excellent advice on these stoves. If anyone wants the contact please PM. I have absolutely no connection with the company.

timmer3 wrote: »

found the same thing myself with clearview stoves, they didn't advertise the outside air kit as an accessory for the stove i wanted but to be fair the chap i spoke to was quite the expert on their products.

fuchia

Hi Macktheknife1,

Could you PM me the contact info.

Thanks

Fuchia

miss indecisive

Hi mactheknife1

Could i get a pm of that company as well please.

Thanks

gman2k

MacTheKnife1 wrote: »

I am looking for the same thing - a range and a stove that ideally should be room sealed (for the HRV).

I spoke with an Irish company recently that gave really excellent advice on these stoves. If anyone wants the contact please PM. I have absolutely no connection with the company.

Hey MacTheknife, can you give us an idea of what excellent advice they are giving out? Save us and them the bother of every boardie ringing them up!

Msmaloney26

Hi,

Hopefully installing similar system, would be very grateful for that contact info via PM is possible.

Thanks.

Dundalkonians

Could someone please pm me those details too. We are getting ready to pour our floors this week and only just realised that we need an external air supply for our stove. Panicking a bit as we had planned our room around a lovely double sided stove and now its not suitable with the hrv, so we really need to find a double sided stove with external air intake and fast.

Help!!!!!!!!

Quack13

HI,

if Mac or anyone else could PM me on this info it would be much appreciated.

Thanks

fuchia

Hi Could someone PM me the details also.

Thanks

Fuchia

Mazotasan

Hi, would appreciate a pm on this also. Again finding information hard to come by...Anyone got feedback on an install yet?

sooty_soupy

Get some advice from someone with a background in the solid fuel heating industry. It is foolish to expect HRV installers can give sound advice on the installation and correct performance of a chimney system designed to remove combustion products from a solid fuel appliance through a property and vent correctly. It's like asking a fish monger to fix your dishwasher.
I give seminars for building control in Northern Ireland and am Chariman of the Norther Ireland Association of Chimney Sweeps. It annoys me no end to see these forums being used to furnish unsafe advice.

We are extrememly busy up here at the moment dealing with rogue retailers popping up all over the place selling stoves, with absolutely no background in the solid fuel industry at all, and it appears that these forums are full of people with conflicting advice from box movers wanting to push you into buying a stove, and the aftermath is yours to deal with, and the advice is pot luck as to how it needs to be installed because more than likely the box mover will not fit it for you.

The Republic was a set of regulations called Document J, and we in teh North have Technical booklet L. Both documents are very similar and are a good source of sound advice on heat producing applainces. Read in conjunction with manufaturers instructions of the chosen flue system and stove, you will not go to far wrong. It's all there in black and white, and then if you are stuck, speak to technical support for the stove or flue and where is the issue?

It really is simple. A solid fuel appliance needs oxygenated air to create complete combustion, and this air movement also helps create the draft through the flue. Too little oxygen and instead of getting carbon dioxide being produced during the burn process, you get incomplete combustion, leading to Carbon Monoxide. Carbon dioxide is 2 parts oxygen 1 part carbon. Carbon Monoxide is 1 part oxygen and 1 part Carbon....and it kills you.

Source a good quality stove that can duct the combustion air directly into the applaince for sleaed homes and you are sorted. Much like the old Baxi fire which ducted the air from outside, leading to a reduction in unpleasant draughts in the room.

If I can be of any help, PM me and I will "try" to get back to you as soon as we can, but often I am used in the Province to pick up the problem ones which take up a lot of my time, but I will do what I can to help.

Best regards

David

Msmaloney26

Hi all,

Sorry for dragging this up but would really like any info or assistance in room sealed stoves. Tech details that I can read or company/tech expertise people I could contact. Would really appreciate.

Thanks

bakerbhoy

Do a search for a thread [ hrv with solid fuel stove ] . I have listed suppliers and makes there. Cannot workout how to link it here

sooty_soupy

Hi MSMaloney, have a look at the post above from myself to understand the concept about solid fuel burning, or any other fuel for that matter. It is clear that HRV companies are reluctant to sign a document to confirm their systems will provide this volume of air while supplying enough for the occupants. This leaves a problem in that the stove will use up the oxygenated air quicker than it can be replenished.

To compensate for this, we have stoves that can have the air it requires to burn ducted DIRECTLY into the stove. This means that the air in the house is all yours and the stove will get it's air from outside independently.

There are a number of stove manufacturers that have this facility including our Shropshire manufactured Clearview range.

Hope this helps

David

PJMCKE

Hi There,

I found several suppliers of the same products in Ireland giving very conflicting information on especially pellet stoves and sotves with boilers. DO NOT TAKE just their word for it. Also I found that as a op said , you need to be familiar with part J of the regs. It is possible that it will require ventilation anyway.

I have yet to purchase but have opted for a woofd burning inset fireplace model from Murphy heating in kinvara. The guy Kieran had built his own house and had HRV and understood exactly what I wanted. Incidently I could not find a pellet boiler/stove that was room sealed. I wanted a unit that was/had a high enough capacity (15-25Kw) to supply whole house space/water heating.
It will be next year before I get mine in and will let you know.

Msmaloney26

Thanks for the info lads,
Myself and builder were having a discussion about this on site today. I dont think he has installed room sealed system before so I want to put him in the right direction. At foundation stages now....so what requirements are needed to be fixed in place now is basically what I need to know.
Thanks again , really appreciate advice.