Any Pro Tips on Insulating Furnace Combustion Air Intake

[20V'er]

Finishing off about 1/4 of my basement into a utility room and small wood shop. Nothing fancy, just finishing the two outside walls, adding some lights and outlets so I have a semi sealed place to work on the odd wood project in the winter time.

Currently my furnace combustion air intake is on an outside wall and is that cheap uninsultated flexiable duct work. It does dump into a 5 gallon bucket on the floor. I plan to replace the current duct work with some flexible insulated stuff and route it so it dumps out right between the water heater and furnace (middle of the house for the most part).

But what can I do to help stop the draft/cold air from coming in and cooling the rest of the finished basement (basement is always colder in winter). I googled around a bit and for every idea, there seems to be another post on why it is a bad idea. Anybody come up with a clever idea that works?

Thanks in advance.

P.S. House is 1930's, every year I pick a few projects to help seal/make it tighter, but it is still an old house (aka drafts). Furnace is gas and guesssing 15 years old. Water heater is gas and is maybe 5 years old. Code requires a fresh combustion air (if it was just the water heater, I would think about deleting it).

 

[Shop Specialties]

If it runs down the wall just run it down till it touches the floor then back up forming what would look like a ' J '. The cold air should get trapped in the ' J ' until the furnace or hot water heater is running then it should draw the cold air in.

 

[Jackfre]

Thankfully. you at least have combustion air for the equipment. Unfortunately you are dumping cold outside air into the space 24/7/365. No control!

Look at the Tjernlund Enforcer. Details are at Tjernlund.com. With this, you could isolate the furnace and water heater from the shop space and spare it the sawdust, etc.

 

[Highbeam]

Sounds like a passive combustion air inlet and not a sealed combustion unit. May as well just open the window. I'm a big fan of sealed combustion intake systems and even have one feeding my woodstove.

 

[20V'er]

Look at the Tjernlund Enforcer. Details are at Tjernlund.com. With this, you could isolate the furnace and water heater from the shop space and spare it the sawdust, etc.

Will do some reading.

Sounds like a passive combustion air inlet and not a sealed combustion unit. May as well just open the window. I'm a big fan of sealed combustion intake systems and even have one feeding my woodstove.

I agree on the big fan of a sealed combustion system, but hard to justify replacing the furnace just for this now. I plan to do the furnace in a few years if I stay in the house.

 

[Mr onetwo]

I have had a little better luck with this control as opposed to the Tjernlund....http://www.fieldcontrols.com/cas3_4.php

 

[rlev11]

I'm no pro but this is what I did for a similar situation in my old house. I have a gas hot water heater,gas steam boiler, and a gas dryer in the same general area of my basement. I used insulated flexible duct to bring the fresh air in and dump it into a box I made out of plywood. I made it about 2 ft. tall and the sides wide enough that the insulated hose fits in the open top of the box with plenty of room around it for the fresh air to escape. I put 2" foam board on the inside of all 4 sides and the bottom of the box (I think it is around r-13). The hose is a couple inches from the bottom of the box. In the winter the insulated box keeps the cold air from from the basement until one of the gas appliances starts running, then I can feel the air coming out of the box until it shuts off. it only makes the basement a couple degrees colder than without the makeup air, but I do notice the rest of my house not being as drafty as the appliances are not trying to get their makeup air thru my old windows of the rest of the house. The bottom of the box also make an awesome beer cooler in the winter. I have also thought of closing off the top of the box, then running smaller insulated flexible ducts from the closed in top directly to near the air intake area of each appliance, my thinking would be that that would isolate the cold intake air even more if the output was directly at the intake of the appliance. I just haven't tried it yet.

 

[Shop Specialties]

I will never use a powered unit again since I found that putting a ' J ' in the cold air intake works. Every single powered unit I have seen has failed at one time or another for a variety of reasons.

 

[Jim_No_Garage]

It does dump into a 5 gallon bucket on the floor. I plan to replace the current duct work with some flexible insulated stuff and route it so it dumps out right between the water heater and furnace (middle of the house for the most part).

But what can I do to help stop the draft/cold air from coming in and cooling the rest of the finished basement (basement is always colder in winter).

Just have the new flex dump into the 5 gallon bucket. That should form the "J" everyone is talking about. I remember that from a Hometime episode years ago.

Jim

 

[20V'er]

I like the idea of the plywood insulated box instead of the uninsulated bucket. Adding that to the list and will see what happens.

Between going to an insulated pipe.
Getting it closer to the appliances that uses the air
Sealing off a 1/4 of the basement with a wall and door that the hose dumps into
Making an insulated box

It should make a difference.

 

[rlev11]

Yea,

I had first just used a bucket, but found that the plastic would get REALLY cold that you could feel anywhere near it. I also had it just sitting on the concrete floor which made the concrete around it icy cold also. that is when I decided there had to be a better way. Like I said, I really don't feel that much of a difference in the basement temperature even on the coldest Pennsylvania days. When the gas dryer or boiler are running and drawing in cold fresh air, the residual heat from the appliance basically evens out the temperature in the room