...old Goodman furnace ... GMP 125-5 9809621618 ... what size is it ???.....

[SmackDabAOK]

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:confused: My current old Goodman ... oops, that's JANITROL furnace ... is GMP 125-5 9809621618, what size is it etc.???

Or any other details.

I just realized that the abreviations (GMP) made me think it was a Goodman, but it's a Janitrol.
But it looks like they are made by the same company, so I guess that's why. Hmmm.

Thanks
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[amd]

Most likely 125,000 BTUs based on the model number.

Sizing based on old equipment is a bad practice.

[SmackDabAOK]

Most likely 125,000 BTUs based on the serial number.

Sizing based on old equipment is a bad practice.



I couldn't agree more.
The unit we have was installed for previous home-owner, & to heat the garage also, due to them storing perishables for a business.

I'm either going to have an outside (qualified) person do load calcs, or else the company I go with for our new furnace install to do the load calcs. I'm thinking about that one.

Our current A/C is a 2.5 ton, per BaldLoonie's previous info from the Model #.
The previous unit quit on us a couple of years ago, likely due to it being too large, to cover for cooling the garage.
Which we do not heat/cool the garage now after we moved in.

[SmackDabAOK]

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I'm assuming these following #'s pertained to the Heat Pump we used to have?
And was this a 48 ton unit, based on the #'s?

If so, then that shows how dramatically it was oversized, since we're not now heating/cooling the garage like previous owner had.

Thanks

[muskyslayr]

No, the 48 refers to BTUs as in 48,000. There are 12,000 BTUs per ton so you have a 4 ton. Or had as the case may be.

[SmackDabAOK]

No, the 48 refers to BTUs as in 48,000. There are 12,000 BTUs per ton so you have a 4 ton. Or had as the case may be.


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Oh yes ... I remember that equation now, I had forgotten that.

Thank you.

It's a good thing that I'm not in this business, ha!
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[amd]

The unit we have was installed for previous home-owner, & to heat the garage also, due to them storing perishables for a business.

That should be downright illegal if it isn't.

I hope you're not using that garage for vehicles. (CO risk) :eek:

[SmackDabAOK]

That should be downright illegal if it isn't.

I hope you're not using that garage for vehicles. (CO risk) :eek:

Well, that was 8 years ago when we moved here. You think there still is a concern?
We're still breathing ... so I guess we'll be OK huh?

Yes ... we park both vehicles in there.

[amd]

You think there still is a concern?
We're still breathing ... so I guess we'll be OK huh?

All it takes is accidentally idling vehicals when the HVAC system is running to pull exhaust fumes into the house.

[fenian]

Well, that was 8 years ago when we moved here. You think there still is a concern?
We're still breathing ... so I guess we'll be OK huh?

Yes ... we park both vehicles in there.

chronic low level co poisoning is just as great a threat.

[RoBoTeq]

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:confused: My current old Goodman ... oops, that's JANITROL furnace ... is GMP 125-5 9809621618, what size is it etc.???

Or any other details.

I just realized that the abreviations (GMP) made me think it was a Goodman, but it's a Janitrol.
But it looks like they are made by the same company, so I guess that's why. Hmmm.

Thanks
.
GMP stands for Goodman Multi Position. In 1998, when this furnace was manufactured, Goodman was still calling the equipment by the original Janitrol name.

It is a 125, 000 Btu furnace and is most likely oversized for whatever you are thinking of using it for.

[SmackDabAOK]

GMP stands for Goodman Multi Position. In 1998, when this furnace was manufactured, Goodman was still calling the equipment by the original Janitrol name.

It is a 125, 000 Btu furnace and is most likely oversized for whatever you are thinking of using it for.
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Appreciate the clarification.

We will be replacing that too-large furnace soon.
I was just trying to learn how oversized it actually was/is for our 1440 sq. ft. ranch-style home built around 1978.

[RoBoTeq]

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Appreciate the clarification.

We will be replacing that too-large furnace soon.
I was just trying to learn how oversized it actually was/is for our 1440 sq. ft. ranch-style home.
OMG! Short cycle much? It's a wonder there's any venting or heat exchanger left on that thing. What kind of idiot put that large a furnace in your home?

[meoberry]

OMG! Short cycle much? It's a wonder there's any venting or heat exchanger left on that thing. What kind of idiot put that large a furnace in your home?

Man that is two sizes to large even for FL.

[amd]

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Appreciate the clarification.

We will be replacing that too-large furnace soon.
I was just trying to learn how oversized it actually was/is for our 1440 sq. ft. ranch-style home.

A house of that size if properly insulated could easily get by with a 50-60k BTU furnace. (In most climates)

[SmackDabAOK]

A house of that size if properly insulated could easily get by with a 50-60k BTU furnace. (In most climates)

We're in Indy

What you said would mean this furnace is at least twice the size we need.
Oh ... I see that meoberry said the same thing for Florida (of all places, ha). That's something else!

The unit we have was installed for/by previous home-owner, & to heat the 2-car garage also, due to them storing perishables for a business.

I haven't timed the cycles, but it hasn't seemed to be severely short cycling thank goodness. But I'm sure it's short cycling to some degree, no doubt.

[RoBoTeq]

We're in Indy

What you said would mean this furnace is at least twice the size we need.
Oh ... I see that meoberry said the same thing for Florida (of all places, ha). That's something else!

The unit we have was installed for/by previous home-owner, & to heat the 2-car garage also, due to them storing perishables for a business.

I haven't timed the cycles, but it hasn't seemed to be severely short cycling thank goodness. But I'm sure it's short cycling to some degree, no doubt.
If it is not short cycling, then there is something seriously wrong with it. And you really need to seperate your ducting from the garage to your house. A garage needs a seperate system that does not share air with your home.

[SmackDabAOK]

And you really need to seperate your ducting from the garage to your house. A garage needs a seperate system that does not share air with your home.



There's no ducting for the garage.

Well ... put it this way ... they had run (crawl-space ducting) a short outlet to the garage. But that is shut off (capped off) now.
There isn't any return vent serving the garage.

The furnace is right there in the garage, so the duct was a short branch off the crawlspace ducting.
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[RoBoTeq]

There's no ducting for the garage.

Well ... put it this way ... they had run (crawl-space ducting) a short outlet to the garage. But that is shut off (capped off) now.
There isn't any return vent serving the garage.

The furnace is right there in the garage, so the duct was a short branch off the crawlspace ducting.
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Good, because even without a return in the garage and even if the return in the garage area were completely sealed, there is still a problem with return.

Let's say there was 300-400 cfm of air being supplied to the garage (anything less would have been worthless), that is 300-400 cfm of air that was not going into the house where the return openings are. So, you have a pressurized garage and a depressurized house. What do you think is going to happen?

[SmackDabAOK]

So, you have a pressurized garage and a depressurized house. What do you think is going to happen?



Actually, I don't know, as I'm "green" to this topic.

So feel free to brief me on it.
Unless that's too involving, then don't worry about it.

(Brevity is the soul of wit ... isn't that a quote? Ahhh, Shakespeare I believe.)

[RoBoTeq]

Actually, I don't know, as I'm "green" to this topic.

So feel free to brief me on it.
Unless that's too involving, then don't worry about it.

(Brevity is the soul of wit ... isn't that a quote? Ahhh, Shakespeare I believe.)
Sorry. That was actually a bit rude of me. I sometimes forget that I am not always discussing issues with someone in the industry.

Anyway, if you have a negative pressure in the home becuase there is more return then supply, and a positive pressure in the garage because there are supply's but no return, the air in the higher pressure zone, the garage, is going to naturally migrate to the lower pressure zone, the house. Through cracks in the walls, under the crawl space and up through the floors and under the door etc., air from the garage is going to constantly be trying to equalize to the lower pressure in the home.

If there could be a perfect seal to prevent air from migrating from the garage to the home, you would still have an air balancing problem that will correct itself in an adverse manner. Conditioned air in the pressurized garage will push its way to the outside, wasting heat. Unconditioned air from outside will come in through windows, doors, chimneys and any other openings into the home. This unconditioned air now has to be conditioned, and you pay to do that.

[SmackDabAOK]

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Ahhh, I see.
Yes, this "pressurize" topic is new to me.

Very interesting, thank you.

Oh, and they didn't have it insulated above garage either. Duhhhh.