Negative chimney draft after radon fan installation

[KTM-MIKE]

What do you think the best solution for this is? I dont want to arbitrarily instal a make up air kit that dumps outside air into the boiler room. I would like to find a set up that connects directly to the boiler to control the ambient room temp. and corrects the draft issue.

Do you know if anyone makes such a unit to mount to a Viessmann boiler?

[Carnak]

http://www.tjernlund.com/commercialInforcer.htm

maybe a cool building is making air fall down the chimney right now also

[KTM-MIKE]

http://www.tjernlund.com/commercialInforcer.htm

maybe a cool building is making air fall down the chimney right now also

Thanks for the reply, but this is in a residential aplication, and I dont want to flood the room, but rather feed the boiler directly.

[Carnak]

condensing boiler piece of cake, but yours goes up a chimney

here is the residential model, you set it to bring in how much air you need, it tempers the cold air with room air

http://www.tjernlund.com/combustionairintake.htm

it brings in air when the boiler fires and is off when the boiler is not firing

[housesmart]

Hoyme out of Canmore Alberta makes a automatic vent damper that opens on a call for heat from the boiler. Once the damper is open, it triggers a end switch that allows the gas valve on the boiler to open. This system prevents cold outside air comming into the boiler room unless the boiler is on.

[firecontrol]

What do you think the best solution for this is? I dont want to arbitrarily instal a make up air kit that dumps outside air into the boiler room. I would like to find a set up that connects directly to the boiler to control the ambient room temp. and corrects the draft issue.

Do you know if anyone makes such a unit to mount to a Viessmann boiler?

The first thing you should do is contact a Viessmann contractor and have them research whether the company has an authorized "fix" for your problem. Manufacturers frown (will sometimes void the warranty) when an aftermarket appliance is added directly to their product.

As we don't have a radon problem in my area I haven't seen first hand what they do to deal with it, but I would think that pulling the entire structure into a negative would solve one problem while creating others as in your case.

[beenthere]

Interesting. Creating a second problem to cover up the symtoms of the first problem.

[hearthman]

Usuallly radon mitigation is subslab suction. If it is depressurizing the house, I would send them a certified letter return receipt and asking them what do THEY plan to do about the problem THEY caused. Most likely, all they have to do is find the leaks and seal the slab better. However, it does point out how sensitive this heater is so you will still need to determine the house depressurization limits through a Worst Case Depressurization Test and combustion analysis.
As previously noted, MUA kits attached directly to a unit may void the warranty just as placing the unit in a negative pressure zone will. If they do not have a listed MUA kit, then you must provide MUA into the CAZ as prescribed in the codes then repeat your testing to verify it works.
HTH,
Hearthman

[mbarson]

Turn off the radon mitigation system. The carbon monoxide from a back drafting appliance will KILL you way before you will ever need to worry about radon. Install a CO detector and get the venting/draft corrected ASAP.

[charliebear]

Call the radon mitigation co and find out what they say. From what I recall, the fans used in radon mitigation are not very powerful, especially compared with kitchen hood fans. The radon system is supposed to relieve pressure under the foundation slab, so unless your slab is very leaky, I find it hard to believe that you would get a bunch of negative pressure from just the radon fan. Typical installation of the radon system calls for sealing up most cracks, and sealing sump covers, etc to minimize this effect. Also, if they don't seal the sump covers, and larger cracks,the radon system will not work as well.