Gas and Oil Home Heating Furnaces - Opinion needed, based on visit from hvac person

HVAC guy stopped buy for review on upgrading to dual fuel.

Currently have gas furnace

I would love for someone to respond and let me know if he is telling the truth.

1. The AC condenser(I guess outside unit and other parts are designed for 4 ton unit). Furnace is goodman 3 ton. (7-8 yr old)
2. Smaller unit was put in due to small entrance to the crawlspace (the guy said it should be 30x36 and I don't think it is. THe old 4 ton is still in crawlspace, since they could not get it out.
3. He also said that the return thing that recovers the air back to furnace is not secured and probably is pushing the air from crawlspace itself back to the house. Some ductswork need repair too.
4. The guy said that I HAVE to get 4 ton unit, but I have to increase entrance to crawlspace to accomdate bigger unit.
5. Two bedrooms upstairs are not getting much air, he said that due to smaller blower(?)
6. dual fuel $4.5K, but at this point, I am not worried about that.

So total damage is $800 to repair ductwork and $2400 for new 100,000 btu trane.

Do I have any other options keeping the 3 ton? doing other things?
Help, :)




:)

If you have a 4 ton condensor on a 3 ton air handler then you should get that straightened out. He sounds on the level to me.

sashka75

First of all, dual fuel systems are excellent and definitely save $$$ if installed in the appropriate climate. They are generally not recommended for areas with frigid winters.

I agree with Matt. The sizing of your furnace(blower) has to be compatible with the size of your outside AC or heat pump condemser. You should not pair a 4 ton outside condenser with a gas furnace that has less than a 4 ton rated blower. Keep in mind also that your ductwork also has to be sized correctly for the amount of air to be moved. I would first recommend a Manual J heat/cool load calculation be performed to correctly size the system your home requires. Get your ductwork thoroughly inspected as to overall condition, insulation properties, size and amount of air required, supply and returns in balance, leaks,etc.

As far as keeping your 3 ton rated furnace will depend on what a load calculation tells you. New furnaces have been designed more compact in recent years.

Good LucK!
:)

1. The AC condenser (I guess outside unit and other parts are designed for 4 ton unit). Furnace is goodman 3 ton. (7-8 yr old)
Someone made a mistake. You should have a 3-ton condenser.



2. Smaller unit was put in due to small entrance to the crawlspace (the guy said it should be 30x36 and I don't think it is. The old 4 ton is still in crawlspace, since they could not get it out.Depends on the brand. A 26"x30" entrance suffices for most 4-ton units provided that you have lots of height inside. Of course, the old unit was fatter than the newer ones.



3. He also said that the return plenum that recovers the air back to furnace is not secured and probably is pulling the air from crawlspace itself back to the house. Some ductswork need repair too.
This is not surprising.



4. The guy said that I HAVE to get 4 ton unit, but I have to increase entrance to crawlspace to accomdate bigger unit.Of perhaps find a different brand. You didn't say what actual dimensions you have. Two concrete blocks wide (32") by 3 blocks high (24") is usually enough .



5. Two bedrooms upstairs are not getting much air, he said that due to smaller blower(?)Or because the duct work is leaking too much.




So total damage is $800 to repair ductwork and $2400 for new 100,000 btu Trane.I can't say anything about the labor or product prices in your area. But you are paying extra for the Trane name. It sounds to me like 3-ton (probably 75,000 BTU) is enough heat. You need either to have the ducts repaired to eliminates leaks, or to have additional ducts to the underheated areas. My guess is that ducting is the problem. Getting a 4-ton furnace won't help unless you have enough duct capacity to utilize the air flow.




Do I have any other options keeping the 3 ton? doing other things?If you are looking for high-efficiency, get a heating/cooling load analysis done. Either you need 4 tons or you don't. If you don't, downsize your heat pump to 3-ton (it will need a matching coil in the supply plenum). If you do need 4-ton (a big house or really hot or cold area), upsize the furnace. You will also need plenty of duct capacity to move 33% more air.


I would take the 3-ton if possible. But if you are planning an addition to your house, build that first before you choose you heating equipment. I personally would rather have a 3-ton that runs for 15 minutes three times during every hour than have a 4-ton that runs for 7 minutes five times during every hour .

The smaller furnace also limits the maximum drain on your wallet when arctic weather comes around. A 100,000 BTU furnace burns almost 1 unit of natural gas per 10 hours of firing --- one-third more than a 75,000 BTU burner.

I am going to crawl in myself and inspect/fix ductwork myself. I don't think it should be complicated.

2. Size of the door to the crawlspace is 15.5x34 inches.

3. currently it is 75,000 and 3 ton furnace.

4. House is 2500 sq feet in Atlanta, Ga, two story 1/2 wood and 1/2 brick pretty standard. I checked a couple of websites, some say 3 ton is fine, while others say that needs to be 5 ton. go figure.

5. Installation in crawlspace has to be horizontal due to height (about 40 inch height.

6. I would assume that duct capacity is fine, since it was originally built with 4 ton system.

So assuming that the 3 ton gas furnace is ok and I fix up most of the ductwork. what would u recommend? right now it's single fuel system and I was thinking about going to dual fuel.

I would imagine that all I need to do is replace the ac unit sitting outside with a heat pump? 3 ton obviously and 13 seer. Anything else?

Also is this appropriate forum for air handler question? was thiking about getting that as well?


thanks again everyone!

If you are going the dual fuel route, the furnace would serve as the air handler. Before buying any equipment do or have done a Manual J, Heating & Cooling Load calculation. This will tell you what size the equipment needs to be.

I am going to crawl in myself and inspect/fix ductwork myself. I don't think it should be complicated.
It shouldn't be except that someone else already failed at it.




2. Size of the door to the crawlspace is 15.5x34 inches.
34" is too small. You need at least 39". That must be a very small furnace you have in there. Is there a wooden frame that could be removed?


3. currently it is 75,000 and 3 ton furnace.75,000 heat is fine.
But you probably need 4 or 5 tons for the air conditioning.


4. House is 2500 sq feet in Atlanta, Ga, two story 1/2 wood and 1/2 brick pretty standard. I checked a couple of websites, some say 3 ton is fine, while others say that needs to be 5 ton. go figure.
Someone has to figure. If you have shade through part of the day, 4-tons is probably all right.
I don't see any way that you need 100,000 BTU heat, though.

5. Installation in crawlspace has to be horizontal due to height (about 40 inch height).Have you considered no gas furnace as an option? You are paying a lot for the furnace when an air handler might work fine. Install a ventless heater in the living area for emergency and supplemntal heat when it gets really cold.

6. I would assume that duct capacity is fine, since it was originally built with 4 ton system.You mentioned 2 bedrooms not getting enough air. But if you have 4T, go with 4T.

So assuming that the 3 ton gas furnace is ok and I fix up most of the ductwork. what would u recommend? right now it's single fuel system and I was thinking about going to dual fuel. I'm thinking you might be a liitle warm in the summer, especially if cold air doesn't get upstairs.

I would imagine that all I need to do is replace the ac unit sitting outside with a heat pump? 3 ton obviously and 13 seer. Anything else?Yes, the a/c coil in your plenum must paired with the heat pump.

I was thinking about getting an air handler as well.Funny that you should mention this. It is an option that I think you should explore.
Also consider moving the furnace upstairs where it is easy to install and maintain and where you can use a vertical unit (a downflow unit could put the heat into the same ducts in your crawl space).

Originally Posted by sashka75
I am going to crawl in myself and inspect/fix ductwork myself. I don't think it should be complicated.
It shouldn't be except that someone else already failed at it.

Ok, I'll crawl and see the damage first and if it's too severe I'll have professional do it.


Quote:
2. Size of the door to the crawlspace is 15.5x34 inches.
34" is too small. You need at least 39". That must be a very small furnace you have in there. Is there a wooden frame that could be removed?


No, what I would have to do is dig a hole next to the house and cut out a small piece of cinderblock/brick venner.


Quote:
3. currently it is 75,000 and 3 ton furnace.
75,000 heat is fine.
But you probably need 4 or 5 tons for the air conditioning.

that's what I have now 3 ton furnace and 4 ton ac


Quote:
4. House is 2500 sq feet in Atlanta, Ga, two story 1/2 wood and 1/2 brick pretty standard. I checked a couple of websites, some say 3 ton is fine, while others say that needs to be 5 ton. go figure.
Someone has to figure. If you have shade through part of the day, 4-tons is probably all right.
I don't see any way that you need 100,000 BTU heat, though.

ac during summer is not a problem. especially since I have whole house fan and several trees around to provide shade.



Quote:
5. Installation in crawlspace has to be horizontal due to height (about 40 inch height).
Have you considered no gas furnace as an option? You are paying a lot for the furnace when an air handler might work fine. Install a ventless heater in the living area for emergency and supplemntal heat when it gets really cold.
Quote:

I've considered going all electrical and it's still on the table. have not looked into ventless. will do so.



Quote:
I was thinking about getting an air handler as well.
Funny that you should mention this. It is an option that I think you should explore.
Also consider moving the furnace upstairs where it is easy to install and maintain and where you can use a vertical unit (a downflow unit could put the heat into the same ducts in your crawl space).

OK. so right now gas furnace is also an airhandler, right? and if I get a heat pump I can use gas furnace or get a separate air handler? I don't think I can move furnace upstairs without rerunning a lot of ductwork. Unfortunately I don't have one main line going upstairs and distributing air, but rather several lines. I also have return vents in every room of the house , so "reducting" everything could get expensive.

that's what I have now 3 ton furnace and 4 ton ac
Please let me clarify:
Your furnace has a built-in 3-ton air handler.
Your air handler must be at least as high in capacity as your condenser.
Right now your airhandler is undersized for the condenser and the coil (hopefully 4T also), could freeze up.



have not looked into ventless. will do so.Some people hate them. I especially like the glowing plaque infrared type or even faux logs.



so right now gas furnace is also an airhandler, right?
Correct.



if I get a heat pump I can use gas furnace or get a separate air handler?Not really. The furnace is you air handler.


Either:
furnace + heat pump + coil = dual fuel system.
or:
Air handler + heat pump + coil ( + ventless heater for emergency/auxilliary heat).



I don't think I can move furnace upstairs without rerunning a lot of ductwork. Unfortunately I don't have one main line going upstairs and distributing air, but rather several lines. I also have return vents in every room of the house , so "reducting" everything could get expensive.
No, I could install the furnace in your neighbor's house and still use your existing ducts.






( Your neighbor wouldn't be too happy about it this, though. :p )