Ask your HVAC questions here.....

24 Replies

Thank you Loren Thomas for the idea! http://www.biggerpockets.com/users/BumperLT

I have been working in the HVAC industry here in Chicago for 5 years. I work in the commercial/ industrial side but same concepts apply to residential. BP has, and still is, given me a great opportunity to learn about REI.

HVAC has AC trouble in my rental unit, the guy said the compressor is locked, he installed hard start relay and says doesnt know how long it will hold up, compressor is noisy as per him and cant be replaced since it doesnt have compatible freon so I need to replace the system.

This post has been removed.

Originally posted by @Rajesh T. :

HVAC has AC trouble in my rental unit, the guy said the compressor is locked, he installed hard start relay and says doesnt know how long it will hold up, compressor is noisy as per him and cant be replaced since it doesnt have compatible freon so I need to replace the system.

 If the system is old , 10+ years, and it truly needed a hard start kit, chances are its on its way out, but there are cases where the system will continue run for several more years. My advice let it play out.

  As far as refrigerant (freon) he his referring to R-22, complete phase out of this not until January 2020, currently contractors can still buy "recycled R-22" with no problem, it's expensive though, and as far as a new compressor, there is never an issue with finding a replacement. But if you go that route, consider the age of the whole system.

Originally posted by @Christina R. :

does  a "fart fan" have to be vented through a stack in the roof per code?

 As you probably already know, all depends on local code. That is all the advice I have on that matter.

If you were to install a unit at your grandmothers house, what brand would it be?

Originally posted by @Shawn Thom :

If you were to install a unit at your grandmothers house, what brand would it be?

Personally, I go with Goodman, has one of the longest warranties, but biggest factor is I get the best price on them. 

   Customer stand point, namebrand should be the least of your worries, go with a contractor that has a reputation of quality work. Installation and design/ retro is the foundation for any hvac equipment, that is where most problems will occur. And if a problem should occur with the unit, the reputable contractor will make sure it is taken care of under warranty. 

Originally posted by @John Yanko :
Originally posted by @Shawn Thom:

If you were to install a unit at your grandmothers house, what brand would it be?

Personally, I go with Goodman, has one of the longest warranties, but biggest factor is I get the best price on them. 

   Customer stand point, namebrand should be the least of your worries, go with a contractor that has a reputation of quality work. Installation and design/ retro is the foundation for any hvac equipment, that is where most problems will occur. And if a problem should occur with the unit, the reputable contractor will make sure it is taken care of under warranty. 

We had Goodman in our personal residence years ago, my rental is getting a Goodman and our personal home now is getting a complete Goodman furnance/ac system replacement.  What's the margin on Goodman products? I think I got a really good deal on my personal home because I learned from bidding out my rental where to start haggling but I'm curious how much they mark up their material. 

"Fart Fan"?  Are we talking "South Park" reference?  I may need one in every room in some of my rentals...

The HVAC in our rental only has one cold air return- a large 2' x 4' grate opening in what is currently used as an office. Is it possible (read:safe) to use this room as a bedroom? If the bedroom door is closed could it restrict oxygen to the natural gas furnace enough that it could cause CO issues?

The furnace is directly below this grate in the basement so its very loud in that room when it kicks on. I don't think that it makes a suitable bedroom, but am curious if its even legal/possible/wise. Thanks!

Originally posted by @Christina R. :
Originally posted by @John Yanko:
Originally posted by @Shawn Thom:

If you were to install a unit at your grandmothers house, what brand would it be?

Personally, I go with Goodman, has one of the longest warranties, but biggest factor is I get the best price on them. 

   Customer stand point, namebrand should be the least of your worries, go with a contractor that has a reputation of quality work. Installation and design/ retro is the foundation for any hvac equipment, that is where most problems will occur. And if a problem should occur with the unit, the reputable contractor will make sure it is taken care of under warranty. 

We had Goodman in our personal residence years ago, my rental is getting a Goodman and our personal home now is getting a complete Goodman furnance/ac system replacement.  What's the margin on Goodman products? I think I got a really good deal on my personal home because I learned from bidding out my rental where to start haggling but I'm curious how much they mark up their material. 

 As far as mark up from the manufacturer to the wholesalers, I have no idea. Mark up from wholesalers to me, this all depends on the amount of business I do with that particular supply house (Johnstone Supply.) My price for a 3 ton, 13 seer system, condenser and evaporator coil, is around $900, add $500 for 80% furnace. Everybody is different when it comes to mark up, several variables need to be taken into consideration. Equipment is the cheap variable, labor is the expensive variable. The lowest quote will, 90% of time, have the least man hours applied. Less man hours equals cut corners and poor quality work. 

Originally posted by @Account Closed :

The HVAC in our rental only has one cold air return- a large 2' x 4' grate opening in what is currently used as an office. Is it possible (read:safe) to use this room as a bedroom? If the bedroom door is closed could it restrict oxygen to the natural gas furnace enough that it could cause CO issues?

The furnace is directly below this grate in the basement so its very loud in that room when it kicks on. I don't think that it makes a suitable bedroom, but am curious if its even legal/possible/wise. Thanks!

 Having one central return is a horrible design, but it's happens, a lot. With that said, if that door becomes closed it will restrict a large amount of airflow. As most home owners know, air filters need to be changed quarterly, if this rule is not followed it will restrict air flow. 

  In your case, it's a door, much worse than a dirty filter. Restricted air flow for cooling: could eventually cause the compressor to go bad ($1000) Restricted air flow for heating: could cause premature failure of heat exchanger ($600) a failed heat exchanger has the potential to leak CO to occupied space. 

  Your return air has no effect on the burner section of a furnace, every furnace has an induced motor for this. Advice on making it a bedroom..... I say no, but it happens, just remember what can eventually happen to the system. 

@John Yanko

The upstairs of my 3 story home is always super hot in the summer while the basement is freezing cold.  I've been looking at zoning my HVAC system.  What brand of products do you like best to retrofit and existing system to a zoned one?

I'm planning on creating 3 zones, one for each floor.  The Honeywell system with wireless thermostats seemed like a good solution.  My existing system is a 95% Carrier 4 ton and is only about 3 years old.  My house is about 2400 sf on the top two levels plus a 60% finished basement.

I'm fairly handy.  I've done plumbing when I've had to, can swap out outlets, lifted a sinking deck and poured new footers, and can put up drywall when I have to.  Is this something I could reasonably do on my own?

Thanks for the input.

@Eddy Dumire

Unfortunately, I have never dealt with zoning on a residential system,so unfortunately no recommendations. Commercial I see Automated Logic, Invensys, and Precision. All of which are for building management. 

  If you are able to follow a wiring diagram and make sense of one and capable of adding dampers to ductwork, you should have no problem. 

Originally posted by @John Yanko :

@Eddy Dumire

Unfortunately, I have never dealt with zoning on a residential system,so unfortunately no recommendations. Commercial I see Automated Logic, Invensys, and Precision. All of which are for building management. 

  If you are able to follow a wiring diagram and make sense of one and capable of adding dampers to ductwork, you should have no problem. 

I'm a licensed hvac contractor and that is horrible advice.   Its a lot more than adding a few dampers and wiring it up.   What are you going to do when 1 zone is calling and that 4 tons of air is trying to travel through 1 ton of ductwork?  You'll blow a compressor when you slug the compressor with liquid refrigerant or you'll crack the heat exchanger by overheating it.   You have to manage the air.   If its a 3 story place, you will not be able to achieve what you want to do without extensive duct modifications to be able to handle that situation.    You will need a bypass and increasing the duct sizes.    If you want to make it work without duct modifications, look into the Carrier Infinity series.    It will require a new condenser and furnace/air handler.    It will reduce the amount of air based upon the zone size that it will calculate for you.   

Residential zoning can be done, but generally needs to be done on the front end when loads etc are calculated. Your best bet is to put a separate unit in the attic just for the upstairs. You will always have a 7-10 degree temperature change from 1st floor to 2nd floor, purely because hot air rises and cold air falls. Unless you have two separate units.

@Brian Mathews

Yea I should have known my place..... For some reason I thought a 95% would have a EC motor w/ mod gas valve, and a zoning controller could simply integrate into the units control board. 

  Btw, hope your having fun with the residential game. 😎

Originally posted by @John Yanko :

@Brian Mathews

Yea I should have known my place..... For some reason I thought a 95% would have a EC motor w/ mod gas valve, and a zoning controller could simply integrate into the units control board. 

  Btw, hope your having fun with the residential game. 😎

Even if it has an ECM motor, unless its a fully communicating system, it won't integrate into the board.  The only company that has zoning that is fully communicating is Carrier with the Infinity/Evolution series.   I realize you're trying to help people out, but be careful what line you cross giving advice out to people regarding repairs in internet land.  You don't know somebody's skill level and they could do serious damage to themselves or their houses and come back to hold you liable.    We are in a lawsuit friendly world.  

@Brian Mathews

Most of my research has also mentioned the need for a bypass valve to handle the excess airflow when only one zone is activated.

I do not have the infinity series, but I do have the performance series.  I'm getting conflicting information on whether mine has a variable speed motor.  I don't think it does.

Regardless, I spent about $7500 for the system I have (Performance series 16 SEER AC, 95% GAS, Heat exchanger).  Maybe I got ripped off.  I don't think replacing the 3 year old system and the duct work (25 years old) is a reasonable solution.  That would cost me $10k+.

Similarly, adding an additional system in the attic would probably cost on the order of $5k (please let me know if I'm way off).

The retrofit zoning parts would only cost me about $1500.

How much would my blown compressor or cracked heat exchanger cost to fix?

I appreciate everyone's advice. 

I hold harmless all parties providing advice in this posting.  In no way will advice provided constitute a contract, agreement, or other legally binding or enforceable arrangement between the parties to perform a specific act of providing actionable advice.  I do further indemnify the parties heretofor for any said advice provided and any resulting damages whether caused directly or indirectly by, to or of myself or my personal or real property, structures, and contents therewith.  If you're still reading you can stop now.  It was a joke.

@John Yanko

 @Rob Bowling

@Eddy Dumire

If you were to go full Infinity system, you're looking at closer to $15K most likely.  A blown compressor under warranty likely $1000+, a cracked heat exchanger poisons you and your family with carbon monoxide.      The problem with adding another system is that your current hvac is sized for your house as it is.    You add another hvac system and you've oversized your current one by subtracting the square footage your new a/c took over.  

I'd suggest you call around to a few local a/c contractors and see what solutions they might be able to offer you.   Installing zoning is not a DIY thing as you can screw something up pretty good if you don't manage the excess air when only 1 zone is calling.   Without seeing the job, I'd suggest manual balancing dampers in main trunklines or individual duct runs to reduce air to areas being overheated or cooled, forcing more air to areas needing more air.   Not closing them off, but reducing.  

What source do you use for furnace filters?  We have 24 units with gas fired furnaces and I change the filters quarterly, so saving a bit on each filter can really add up.  Thanks.

@John Yanko quick question..... looking to buy a duplex and both gas heaters are cooked.. each is 28 years old and i wanna go new..

   The current gas heaters are lennox heaters... whats a rough idea on what i would cost two get two new ones installed....  this way i can make a lower offer on the house

 thanks 

I recently put an offer on a condo I want to flip. When I first walked in the A/C was on but it wasn't very cool at all. It's a foreclosure so I'm assuming someone from the HOA goes in there to turn it on and off and check up on things. I noticed very little to no air coming out of the vents. The A/C line going into the condenser had ice around it. I'm assuming the condenser is frozen up and freon is bypassing the condenser, which is also the cause for no air flow. The furnace is old and makes a ton of noise so it will definitely need to be replaced. The A/C compressors are on the roof (it's only 2 stories). I don't know if this thing is on all the time or if someone goes in the unit and turns it off. I would've turned everything off and let the fan run to at least let the ice thaw, but hey, I don't own the condo. What's the chance that I could just replace the furnace and that the A/C would be salvageable? What's the average price for a gas furnace replacement in a 1000sqft condo?

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