make-up air freezes the basement pipes?

[Mike]

We recently had a radon mitigation system installed in our basement. The contractor also installed a passive make-up air vent (a pipe connected to the outside to let fresh air in) in the basement to prevent backdrafting of furnace.

We have a forced air heating system. The furnace is in the basement and the basement IS heated. But the thermostat is on the first floor.

Should I be concerned about water pipes (in the basement) getting freezed by the cold make-up air in the winter? We live in New England. It can get pretty cold in the winter.

If yes, how should I handle it? I don't want to close the make-up vent because I did notice some backdrafting when it's closed.

[Joseph Meehan]

You don't want to close off the make-up air. Not if you like living. BTW you sound like a good candidate for a CO detector if you don't have one. I highly recommend one.

I am not sure of what is going on in your systems. My guess is you may do well to enclose the furnace in its own room and feed the make up air directly to it, or replace it with a new high efficiency unit that will have a sealed system and you can connect the make-up air intake directly to it.

[m Ransley]

An old house should not need make up air, a new extremely tight house maybe yes. A blower door test is needed to find out air exchanges per hour. Does it back draft when dryer and exuast fans are on. This could be a chimney issue, wind or cold flue, or blockage as in debris or dead bird, I would look into it more.

[buffalobill]

i don't know what would happen if you turned the radon fan off for winter.

there sure is lots to read at

and test kits at search for freezing alarms frost alarms heat tape

[Mike]

Thanks guys for your reply.

I don't want to turn off the Radon mitigation system for the winter because the Radon level was quite high without it.

I don't want to close the make-up air vent for safety reason as Joseph said. As I mentioned, I did notice backdrafting of furnance when the make-up air was shut off.

I want to know if anybody has experienced or heard of pipes in a HEATED basement got frozen because of make-up air. If yes, any relatively simple way to fix the problem.

I got some useful suggestions. More are appreciated.

[kevin]

We put a second backup thermostat in our basement for just this reason. We wired it up so that if the basement drops below 40 or so the furnace turns on (regardless of how hot it might get upstairs). Not really ideal, but a few times on really cold nights it has tripped. If I hear the furnace turn on, and can go adjust the heat vents to put more heat into the basement. Really I'd like to have some sort of buzzer or indicator light that alerts me to the fact that the basement is getting too cold.

I didn't have handy a thermostat that went that low, actually, so I just installed a mercury-switch type one at an angle, and subtract 20 from the scale. Tricky to get the angle right, but seems to work.

-Kevin

[Goedjn]

In decending order of cost-effectiveness:

Heat tape on the pipes. Direct external air supply for the air-using appliances that AREN'T radon mitigation. A heat-exchanger for the radon system, if it's supply and exhaust are both ducted.

[Joseph Meehan]

I have seen pipes freeze in a heated first floor. It really depends on a number of factors and it could happen in a basement under the right or wrong conditions.

Assuming the make-up air outlet is not near the pipes, you should be safe, but get something cold enough and it will freeze. I suggest you keep a thermometer down there and check it from time to time when it is really cold out. Move it around to find the cold spots and how cold it is around the pipes. You can even buy cheap digital models that will hold the lowest and highest temperature until reset. You should get a good idea about the conditions you will need to worry about. You also can get a warning device that will alert you if it gets close to freezing.

[Trekking Tom]

Here's what I did for the same thing. My boiler was in it's own little room, when the makeup air was installed with the new boiler I had them create a duct for it to follow the basement wall to about 6" from the floor. This way the heat the boiler gives off does not go out the vent during the off cycle. Once the cold air from outside equalizes the bottom foot or so of the boiler room it stops coming in until needed for the combustion process.

Tom