Cold combustion air intake making basement cold

[danski0224]

Yea but not enough to justify out side air being brought in , unless it's a code issue .

Those single pipe power vent water heaters use a ****-ton of indoor air. Way more than a regular water heater.

Those water heaters are no different from a regular atmospheric vent water heater in construction. The power vent dilutes the exhaust with a massive amount of indoor air pulled through a restrictor plate to bring the exhaust temperature down low enough to use PVC pipe to vent it.

They are not "high efficiency".

Far as I know, the only true high efficiency tank water heater is a 2 pipe AO Smith Vertex.

 

[danski0224]

I can’t believe they didn’t connect the combustion intake directly to outside air with PVC.

Jay

Why? It costs more.

The builder dictates the quality of the HVAC install outside of required codes... and the homeowner pays.

 

[danski0224]

Hi Guys,

I've got a new house with a high efficiency furnace. The basement is insulated well and the house is very tight. As you can see from the pictures the cold air intake for the furnace combustion comes in and the pipe is open near the floor.

It's basically spilling out cold air into the basement constantly which is making the basement pretty cold. So I was looking for suggestions on how to stop this from happening.

I've been doing some research and some suggest to try putting a "J" pipe connecting to the cold air intake pipe to keep the cold air from spilling out all the time.

Other suggestions are to use a mechanical damper that is activated to open when the furnace turns on.

And other suggestions are to close off that entire area of the furnace and water heater so that the cold air stays in there.

The last 2 are a little expensive and the first one doesn't sound like it'll work (I've already tried a 5 gallon bucket under the pipe and it didn't do anything - cold air still spills over the edge of the bucket).

Suggestions?

Sorry about that. I guess I could've uploaded them like that also. Thanks for the help guys.

But yea I will try to get some pics of the hot water heater setup tonight.

That pipe is code required combustion air for your furnace and water heater. It is NOT a "fresh air intake". The combustion air pipe provides a controlled air leak, otherwise the combustion air will come form other sources.

The pipe inside a pipe trick works, but a 5 gallon bucket isn't tall enough.

There is a solution with a powered intake fan that is electrically connected to the furnace and the water heater, it brings in combustion air when the appliances are on.

Proper implementation takes knowledge and can be expensive (power fan or proper appliances and vent connections). The builder nixes the expensive stuff and the code is really a standard of minimums.

The other solution is (1) pipe the furnace intake air to the outdoors according to the manufacturer instructions and (2) get a true 2-pipe (direct vent) water heater. If both of these are performed, the combustion air pipe can be eliminated for those appliances. Whether or not combustion or makeup air is needed elsewhere in the home is another issue.

 

[Showkey]

Those single pipe power vent water heaters use a ****-ton of indoor air. Way more than a regular water heater.

Those water heaters are no different from a regular atmospheric vent water heater in construction. The power vent dilutes the exhaust with a massive amount of indoor air pulled through a restrictor plate to bring the exhaust temperature down low enough to use PVC pipe to vent it.

They are not "high efficiency".

Far as I know, the only true high efficiency tank water heater is a 2 pipe AO Smith Vertex.

Does not matter it still does not need a make up air supply. The power vent water heater uses about $8-$15 in NAT gas in a month. If your concerned about “massive” amount of air from the water heater........measure the air used by that furnace next to it that should have be drawing outside air. The reason power vent water heater don’t use cold outside air they don’t want the exhaust to condense.

Bradford has a 90% eF Series High Efficiency Power Vent Model but at $10 per month for NAT gas the ROI is not great when a regular power vent is 70-75%.

http://www.bradfordwhite.com/products/power-vent-2

 

[danski0224]

The air exhausted by the single pipe furnace or water heater comes from somewhere...

The air used for combustion comes from somewhere too.

It isn't always about ROI.

 

[brewchief]

Does not matter it still does not need a make up air supply. The power vent water heater uses about $8-$15 in NAT gas in a month. If your concerned about “massive” amount of air from the water heater........measure the air used by that furnace next to it that should have be drawing outside air. The reason power vent water heater don’t use cold outside air they don’t want the exhaust to condense.

Bradford has a 90% eF Series High Efficiency Power Vent Model but at $10 per month for NAT gas the ROI is not great when a regular power vent is 70-75%.

http://www.bradfordwhite.com/products/power-vent-2

The water heater will use a ton of air to dilute the high temperature flue gasses down to a temperature that the pvc can withstand, if you block the dilution air inlet at the ventor motor the pvc will turn brown and sag from the heat, I've seen it happen. The furnace has a secondary heat exchanger that lowers the flue gasses temp to the point they condense, the water heater doesn't have that so they simply add a bunch of room temp air to the hot air to make warm air.

 

[eddieK]

OK guys, maybe this discussion is only for high efficiency furnaces & water heaters. I've been in & lived in many houses with older gas/propane furnaces & water heaters and I've never heard of or seen any piping to bring air into the house. The only piping was a vent pipe that both units shared to let the exhaust out. So what's going on?

You do not have to pipe it if there is a way to chase the air through a void or a chase, as in floor joists, ceiling joists bays...In that case you usually notice combustion air screens in closets, older installs in closets allowed just a louvered door. 1 hi and one low

And if it is in a ventilated space, garage or basement the "free" air is combustion air.

 

[eddieK]

OK here are a couple pictures of the water heater. It's definitely exhausting outside.

A couple more of the furnace which is is rated at 96% efficiency. It is also exhasuting outside but the intake air is coming from the smaller pipe and using the basement air (I can't believe it's not coming from the outside ).

Sp the other duct workhas to be for the make up air. I don't know if you can see from the other pics ealier in the thread but there is also a second duct coming from the outside (for makeup air I presume) that is going directly into the cold air returns in the house duct work.

I know it's pulling outside air from this pipe because it is directly below our bathroom floor and that spot gets so cold it feels like you're standing on ice when the furnace is running.

The house must be pretty tight because the floor doesn't feel as cold in this area when the furnace is not running.

To answer the previous question - Yes they did a "blow test" on the house before we moved in and it passed. There is a sticker on the main breaker box stating as such. All the duct work seems are sealed and taped and the rim joist around the perimeter of the basement are sealed with caulk and insulated.

You can route it outside...it's only 2" PVC. That particular install is pretty much code, except in the zones I work in...combustion piping MUST be rigid or a chase.

 

[eddieK]

Why? It costs more.

The builder dictates the quality of the HVAC install outside of required codes... and the homeowner pays.

It costs more to run the TWO ducts outside and probably required a bit of cutting (additional labor) to do that.

It would have been cheaper to run the PVC...Now I have had homeowners AND general contractors complain about aesthetics..."that PVC pipe sticking outside is ugly". A combustion air vent with ducts just terminates with a louvered screen or a T top.

I wish people would not knee jerk react about contractors and their GREED. I know few that are RICH. I do know many that constantly are attempting to lose a lot less money than they end up losing, because of things way outside of their control...excessive trips to projects to appease unnecessary complaints from people that understand very little about the project they try to micro manage drain profits rapidly.

What things cause profit loss?

Delayed decisions by homeowners (sometimes months)
Delays and special delivery costs for special order items when homeowner decides "that doesn't look like I thought it would"
Alterations and not approving the additional work orders they generate
Equipment and Parts costs increases as the project drags along
In 2004 I recall gas prices suddenly jumping to $4.00 a gallon

 

[brewchief]

It costs more to run the TWO ducts outside and probably required a bit of cutting (additional labor) to do that.

It would have been cheaper to run the PVC...Now I have had homeowners AND general contractors complain about aesthetics..."that PVC pipe sticking outside is ugly". A combustion air vent with ducts just terminates with a louvered screen or a T top.

I wish people would not knee jerk react about contractors and their GREED. I know few that are RICH. I do know many that constantly are attempting to lose a lot less money than they end up losing, because of things way outside of their control...excessive trips to projects to appease unnecessary complaints from people that understand very little about the project they try to micro manage drain profits rapidly.

What things cause profit loss?

Delayed decisions by homeowners (sometimes months)
Delays and special delivery costs for special order items when homeowner decides "that doesn't look like I thought it would"
Alterations and not approving the additional work orders they generate
Equipment and Parts costs increases as the project drags along
In 2004 I recall gas prices suddenly jumping to $4.00 a gallon

The 6" intake needed to be run for the water heater regardless so running a 3" pvc pipe for the furnace would have added cost.
Having the furnace intake run outside also allows for the possibility that it could get clogged with ice or snow. Drawing from the inside you can also argue that you will get a more consistent temp for combustion and thus be able to get a slight bump in efficiency.

I don't know exactly where the OP is at but that is a very typical new construction install here in MI, the builder will squeeze the sub contractors as tight as possible so that the money saved on mechanicals can go towards fancy kitchens and such.


The ideal fix would be to pipe the furnace intake outside and replace the water heater with a two pipe direct vent unit. That combustion air pipe could then be deleted.

 

[Showkey]

The water heater will use a ton of air to dilute the high temperature flue gasses down to a temperature that the pvc can withstand, if you block the dilution air inlet at the ventor motor the pvc will turn brown and sag from the heat, I've seen it happen. The furnace has a secondary heat exchanger that lowers the flue gasses temp to the point they condense, the water heater doesn't have that so they simply add a bunch of room temp air to the hot air to make warm air.

Who said anything about blocking or restricting the power vent on the water heater?

 

[101mph]

Just wanted to state that this house was a spec home. Yes it was new (actually it was built in 2016) when we bought it, but the home was essentially complete. We only had the builder change/fix a few minor things before we moved in and I didn't even really think much about this furnace HVAC setup when I looked at it.

It was only after living here for a couple months that I was bothered by the basement being so cold. So I started to investigate where and why the cold was down there. This duct I feel is the source of it.

We are in Oakland County Michigan

 

[danski0224]

The 6" intake needed to be run for the water heater regardless so running a 3" pvc pipe for the furnace would have added cost.
Having the furnace intake run outside also allows for the possibility that it could get clogged with ice or snow. Drawing from the inside you can also argue that you will get a more consistent temp for combustion and thus be able to get a slight bump in efficiency.

I don't know exactly where the OP is at but that is a very typical new construction install here in MI, the builder will squeeze the sub contractors as tight as possible so that the money saved on mechanicals can go towards fancy kitchens and such.


The ideal fix would be to pipe the furnace intake outside and replace the water heater with a two pipe direct vent unit. That combustion air pipe could then be deleted.

+1

Same thing I posted +/-

 

[eddieK]

The 6" intake needed to be run for the water heater regardless so running a 3" pvc pipe for the furnace would have added cost.
Having the furnace intake run outside also allows for the possibility that it could get clogged with ice or snow. Drawing from the inside you can also argue that you will get a more consistent temp for combustion and thus be able to get a slight bump in efficiency.

I don't know exactly where the OP is at but that is a very typical new construction install here in MI, the builder will squeeze the sub contractors as tight as possible so that the money saved on mechanicals can go towards fancy kitchens and such.


The ideal fix would be to pipe the furnace intake outside and replace the water heater with a two pipe direct vent unit. That combustion air pipe could then be deleted.

That squeeze is common everywhere.

 

[eddieK]

Just wanted to state that this house was a spec home. Yes it was new (actually it was built in 2016) when we bought it, but the home was essentially complete. We only had the builder change/fix a few minor things before we moved in and I didn't even really think much about this furnace HVAC setup when I looked at it.

It was only after living here for a couple months that I was bothered by the basement being so cold. So I started to investigate where and why the cold was down there. This duct I feel is the source of it.

We are in Oakland County Michigan

Your reaction (ignoring heat and or cooling) is very common(not a dig, just happens to be the way people are). I have, over 40 years, realized people just "expect" some things to be. While building custom homes (as an HVAC contractor) I have recommended many things that get turned down because of aesthetics. I write this up and let them know during the project that it is their decision, they must choose between operation and aesthetics.

This way when they complain down the road it is recognized that I did not "cut corners" but was limited by someone else' decision.

This is why I preferred remodel, people had lived in the home and had experienced unsatisfactory conditions, so when it came to aesthetics and operation, now operation carried much more weight.

 

[101mph]

Your reaction (ignoring heat and or cooling) is very common(not a dig, just happens to be the way people are). I have, over 40 years, realized people just "expect" some things to be. While building custom homes (as an HVAC contractor) I have recommended many things that get turned down because of aesthetics. I write this up and let them know during the project that it is their decision, they must choose between operation and aesthetics.

I understand. But trust me I looked carefully. I saw that the house was well sealed up and that the builder did good work. He used quality materials for the most part in the house etc. etc.

I just had no idea at the time about makeup air and I'm not an expert in HVAC. But this isn't my first rodeo (I've owned 4 houses up until now). I'm just looking for a possible solution and this thread has been very helpful.

 

[Jackfre]

I think that I would ask the builder to please point out the other half-assed things he did to keep you from having to discover them. First, I would run that intake pvc to the outside and terminate it according to the manuf installation instructions. If that is done you may have enough cubic space as "unconfined" to eliminate or dramatically reduce the size of the pipe entering the basement.

 

[LS6 Tommy]

Running the 2" combustion air to the outside , is not code required.

It is if the furnace is using return air from the same room room it's located. The OP's is not, but the whole job looks sketchy to me...

Tommy

 

[danski0224]

but the whole job looks sketchy to me...

It looks like a typical semi-custom home HVAC job to me. Better than many tract home installs I have seen.

Plenty of room for improvement (often for not much more money at the construction phase), but I'm sure that it meets local codes...

 

[eddieK]

I think that I would ask the builder to please point out the other half-assed things he did to keep you from having to discover them. First, I would run that intake pvc to the outside and terminate it according to the manuf installation instructions. If that is done you may have enough cubic space as "unconfined" to eliminate or dramatically reduce the size of the pipe entering the basement.

The minimum is already installed. At least in my neck of the woods

 

[eddieK]

I understand. But trust me I looked carefully. I saw that the house was well sealed up and that the builder did good work. He used quality materials for the most part in the house etc. etc.

I just had no idea at the time about makeup air and I'm not an expert in HVAC. But this isn't my first rodeo (I've owned 4 houses up until now). I'm just looking for a possible solution and this thread has been very helpful.

I understand it is not your first rodeo. But every single house is unique, including tracks. That is what I meant by remodel work, they have lived in THIS house and experienced IT...so now my recommendations have weight.

 

[eddieK]

The 6" intake needed to be run for the water heater regardless so running a 3" pvc pipe for the furnace would have added cost.
Having the furnace intake run outside also allows for the possibility that it could get clogged with ice or snow. Drawing from the inside you can also argue that you will get a more consistent temp for combustion and thus be able to get a slight bump in efficiency.

I don't know exactly where the OP is at but that is a very typical new construction install here in MI, the builder will squeeze the sub contractors as tight as possible so that the money saved on mechanicals can go towards fancy kitchens and such.


The ideal fix would be to pipe the furnace intake outside and replace the water heater with a two pipe direct vent unit. That combustion air pipe could then be deleted.

It's not an intake. It is combustion air (free air movement). If it was required for the water heater and the HVAC contractor routed the 2" combustion air to the outside, then the plumber would have been installing the combustion air for the water heater. In both cases, the sub contractors have to do this within the quote they originally provided, in the grand scale of these projects it is cheaper to just do it, rather than have to return to do so.

I can go to any project anywhere and find flaws(including my own), I bet in whatever trade or profession you have you could as well.

I just get real tired of people generally assuming every contractor everywhere is cutting corners and providing sub standard work. It gets old. Especially when non trade professionals start tearing projects apart and declaring things that they know very little about.

Tell me, what is the cost difference between the two water heaters you are speaking about? Which one was listed on the title 24 page?

 

[danski0224]

Technically, there should be 2 combustion air outlets, fed by separate ducts, terminating 1 foot above the floor and 1 foot below the ceiling. Maybe those details are not in the provided images.

The (sub) contractor is typically providing a product that fits within the scope of work allowed by the "winning" bid. That can become a slippery slope when the employees of that subcontractor are on a performance based pay or other incentive program that encourages corner cutting as a means to increase pay or generate a bonus.