750 square foot condo...2 1/2 ton AC with 75,000 btu gas furnace

(Greg Fox) #1

Seems like overkill to put a 2 and 1/2 ton cooling system in a 750 square foot condo, and a 75,000 btu gas furnace for this space.....Can anyone think of a good reason why they would use this configuration on such a small one level condo? This equipment was just installed in this 45 year old unit in the last 30 days. All new

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(Roy Lewis, CMI - North Florida Inspector) #2

I don't know about the furnace, but the 2.5 ton is to large for such a small space.
It will cycle too quickly and leave lots of moisture behind.

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(Stewart Mussolum) #3

Yes, overkill. A/C will short cycle and not run long enough to remove humidity. The home will be cold but humid and be a great way to grow mold.

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(Greg Fox) #4

I've seen 75,000 btu gas furnaces for entire houses that are 1500 to 2000 square feet. Does anyone know what the rule of thumb is for sizing a 75,000 btu gas furnace?

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(David A. Andersen, TN HI# 40) #5

Can I say that too?!

It "MIGHT" be too big.
Where is your load calc?

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(David A. Andersen, TN HI# 40) #6

Hay Mr. Fox,

Want a job?
You do the inspection to the TN Standards and I'll do all that other stuff...

I'll even do the report.

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(Greg Fox) #7

[quote="dandersen, post:6, topic:81041"]

Hay Mr. Fox,

Want a job?
You do the inspection to the TN Standards and I'll do all that other stuff...

I'll even do the report.
[/QUOTE]

Hey David....I heard you were a serious F'ING PRICK from other inspectors...Thanks for confirming that.....Adios

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(Jeff Spencer) #8

Around here, some of the one truck heating and cooling companies do their load calculations as 600 sq ft per ton. That is of course thrown out when they only have a 2.5 ton ac sitting in their warehouse.

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(David A. Andersen, TN HI# 40) #9

[quote="gfox1, post:7, topic:81041"]

Hey David....I heard you were a serious F'ING PRICK from other inspectors...Thanks for confirming that.....Adios
[/QUOTE]

Hey, no problem!

I see over and over again that you are trying to analyze things like HVAC that is totally outside the scope of your inspection and you probably will eventually get into trouble over it at some point in time.

Just thought I'd offer to do the HVAC and building science stuff you seem to want to get involved with, until you can get on your feet. I avoid home inspections at all cost and would prefer someone else to do the other stuff.

Thought you might want a job doing my home inspections, which you do best and get some help on what you do worst.

I guess your "F'ING PRICK " attitude will prevent you from considering anything like that. Just keep doing what you do...

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(Roy Lewis, CMI - North Florida Inspector) #10

[quote="dandersen, post:9, topic:81041"]

Hey, no problem!

I avoid home inspections at all cost and would prefer someone else to do the other stuff.

[/QUOTE]

Then you need to find a new home.
You sure entered a dead end street .
This an inspector forum. What are you ?

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(David A. Andersen, TN HI# 40) #11

I'm the guy that figures out what to do with the "Recommend Further Evaluation" entries in the Home Inspection Reports from Nashville, Tn.

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(David A. Andersen, TN HI# 40) #12

I hate to turn down work, and I would rather have someone do home inspections for my clients and allow me more time to deal with the serious issues that seem to fill my plate.

A lot of home inspectors advertise that they inspect a lot of components that in reality they barely scratch the surface on. This is not necessarily a good thing for the client. It gives a false sense of security and a false inspection in some cases.

Everybody looks to make the big bucks by adding on their ancillary services, and it's not that they don't have the desire or resources, they don't have the time to accumulate the experience.

Would you agree to get paid the going rate of your inspection without the marketing requirements, without the reporting requirements, without the liability, without having to invest in all that ancillary service stuff?

At this point I would take myself up on my own offer!
Let me do a home inspection to the State of Tennessee inspection standards, take some pictures, forward them to you and go home!

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(Roy Lewis, CMI - North Florida Inspector) #13

I don't see engineer anywhere in your sig line .

[quote="dandersen, post:11, topic:81041"]

I'm the guy that figures out what to do with the "Recommend Further Evaluation" entries in the Home Inspection Reports from Nashville, Tn.
[/QUOTE]

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(Charley L. Bottger) #14

[quote="rlewis5, post:13, topic:81041"]

I don't see engineer anywhere in your sig line .
[/QUOTE]

Roy there is a lot of things you don't see.

Two ears one mouth;-)

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(Roy Lewis, CMI - North Florida Inspector) #15

I've been told by a friend that you and David are good guys and know what you are talking about.

My apology to both of you .
It just seems to be a lot of people on this board that want people to believe they are experts and they are not.
That is why I'm cautious .

Roy Lewis

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(Robert J. Spermo, TREC # 4726) #16

I would never call an HVAC unit too big or too small unless I had completed a thorough load calculation. In south Texas the size of the furnace is dictated by the size of the air conditioning unit. All of our furnaces are "oversized" in that we do not need that amount of heat output. However, we do need the size fan that comes with the furnace to push the required cool air.

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(Sean Fogarty) #17

Since no one else is going to actually try and help you Mr. Fox I will make a suggestion.
Obviously you know the unit is new and doesnt seem to work for the size of the dwelling under common rule of thumb sizing.

Have you considered calling the company that put it in, and ask them why?

I have in the past suggested units be evaluated because of gross oversizing but it has to be pretty obvious. Like a 5 ton for a 1200 sf home.

For every guy that says your issue is fine, you will have another come along and try to say you should have caught this issue during your inspection. I had one dork try and say since the unit was 16 years old and 1/2 smaller than it should be, I should have found it.

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(Erik Schmidt) #18

My two bits - re size of furnace, 75,000 btuh is this input or output? An 80% AFUE furnace 75,000 input will produce 60,000 btuh for heating the house, the rest goes up the chimney.

To properly determine furnace size and cooling requirements you need to calculate heat loss and heat gain. This requires having a full set of prints and specs for the house or unit. Determine the exposed area of all walls, windows, ceilings, doors, basements, crawls etc., find R or U values for all of the materials and components between the building envelope of the house and the outside. Using Manual J calculate the heat loss and gain for the building factoring in your location, the exposure and compass orientation of the building, nearby trees, houses etc..
When you are done, maybe four or five hours later, call your friendly furnace dealer, and discover that your favorite appliance brand only has four sizes to choose from and 60,000 BTUH heat and 2 tons of cooling are the smallest they have (WTF did I just waste four hours for?).

Sixty thousand BTU would easily heat a new house in the 1000 square foot range hear in Edmonton where the outside design temperature for heating is -25 F for heat and 82F. I am thinking it is less and more respectively in me Nashville Tennessee

Some new furnaces now have multiple btuh outputs, equally efficient at even 40% of the rated max.

The rule of thumb rule I propose is to contact a competent. experienced and local HVAC contractor and ask them what they would have put in.

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(Peter W. Bennett, NJ Lic# 24G100037100) #19

How about the two 50k btuh 80% and 90% efficient systems in a 3,200 sq ft home, with 9 ft ceilings, and a finished basement? Undersized? Not my call but written up as questionable.
I mentioned manual J and all walls, windows, ceilings, doors, basement, check out R or U values for all of the materials and components between the building envelope, factoring in the location, the exposure and compass orientation of the building, nearby trees, houses.

The buyer who is an attorney, said he felt the same and would be contacting the builder.
Can't wait to hear the results.

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(Charley L. Bottger) #20

[quote="pbennett1, post:19, topic:81041"]

How about the two 50k btuh 80% and 90% efficient systems in a 3,200 sq ft home, with 9 ft ceilings, and a finished basement? Undersized? Not my call but written up as questionable.
I mentioned manual J and all walls, windows, ceilings, doors, basement, check out R or U values for all of the materials and components between the building envelope, factoring in the location, the exposure and compass orientation of the building, nearby trees, houses.

The buyer who is an attorney, said he felt the same and would be contacting the builder.
Can't wait to hear the results.
[/QUOTE]

Very questionable

I had a 3100 SQ FT 2 story last week with one 4 ton split, furnace in the basement trying to push air to the second floor attic with outlets in the ceiling. Two returns both down stairs neither of which was near the stairs. With the A/C operating the upstairs was like a oven and the down stairs was a meat locker. Occupants can not be happy with this type of heating and cooling so I tell them what I think :D;-)

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