What size furnace?

[H.Huester]

Have a '74 31' Excella 500 that came without a furnace - will put a new one in. It came with a 30k BTU unit, but comparable size new AS come with a 34K BTU unit. Read that you can oversize the furnace resulting in fast and significant temperature swings. What are your thoughts? Thanks, Heinz

[Inland RV Center, In]

Originally Posted by H. Huester

Have a '74 31' Excella 500 that came without a furnace - will put a new one in. It came with a 30k BTU unit, but comparable size new AS come with a 34K BTU unit. Read that you can oversize the furnace resulting in fast and significant temperature swings. What are your thoughts? Thanks, Heinz

The equal to the original, which was very adequate, is NT30SP, a 30,000 BTU unit, best I can recall.

I will not be in my office near any specs until Monday.

Andy

[mimiandrews]

Same question for our '66 model 22' Safari. What is the appropriate replacement for the NT20--that's what the manual says it came with.

[Inland RV Center, In]

Originally Posted by mimiandrews

Same question for our '66 model 22' Safari. What is the appropriate replacement for the NT20--that's what the manual says it came with.

I can give you the suggested replacement, but not until Monday.

Andy

[mimiandrews]

Thanks, Andy. Have a great rest of the holiday!

I'll check this thread on Monday or Tuesday.

[mimiandrews]

Originally Posted by Inland RV Center, In

I can give you the suggested replacement, but not until Monday.

Andy

Hi Andy,

Had a chance to look at those furnace specs yet?

[Inland RV Center, In]

Originally Posted by mimiandrews

Hi Andy,

Had a chance to look at those furnace specs yet?

I have been a little under the weather, but I will be in the office tomorrow.

Andy

[bhayden]

Originally Posted by H. Huester

Read that you can oversize the furnace resulting in fast and significant temperature swings. What are your thoughts? Thanks, Heinz

You could but that's exactly the opposite of what you want. Don't go any bigger than what was originally spec'd. If you can't get that get the next smaller size. You want to maintain an even temperature and avoid short cycling the furnace. A two stage furnace in a trailer would be ideal. You'd rarely use the high setting. A 34K BTU furnace in a 31' trailer is already the equivalent of a 120k BTU furnace (good for a 3,000 sq ft house) in a 760 sq ft studio appartment.

[Inland RV Center, In]

Originally Posted by mimiandrews

Hi Andy,

Had a chance to look at those furnace specs yet?

The original furnace in your trailer was either a 20 or 22,000 BTU model, best I remember.

The 24,ooo BTU models are gone.

The two choices are a 19,000 or 30,000 BTU models.

But, the difference in price is $18.00.

Therefore I would suggest installing the NT30SP model.

It's better to have a little more, than not enough heat.

Andy

[mimiandrews]

Thanks!

[mimiandrews]

Originally Posted by Inland RV Center, In

The original furnace in your trailer was either a 20 or 22,000 BTU model, best I remember.

The 24,ooo BTU models are gone.

The two choices are a 19,000 or 30,000 BTU models.

But, the difference in price is $18.00.

Therefore I would suggest installing the NT30SP model.

It's better to have a little more, than not enough heat.

Andy

Which one of those furnaces would fit the cabinet and ducting best? Original furnace was an NT20, if the manual is right.

[Inland RV Center, In]

Originally Posted by mimiandrews

Which one of those furnaces would fit the cabinet and ducting best? Original furnace was an NT20, if the manual is right.

The dimensions for the 19,000 BTU Suburban is 9 1/2" wide, 22 1/2" deep and 9 3/8" high.

The dimensions for the 30,000 BTU Suburban is 12" wide, 23" deep and 12 1/2" high.

Andy

[bhayden]

Originally Posted by Inland RV Center, In

The original furnace in your trailer was either a 20 or 22,000 BTU model, best I remember... I would suggest installing the NT30SP model. It's better to have a little more, than not enough heat.

Andy

Why on earth would you want 30,000 btu to heat ~200 sq ft of living space. That's 2-1/2 tons of heating capacity. Way more is not better than the right amount. Fast temperature swings are not what leads to comfort. You want air circulation and an even temperature. It's also a lot more efficient. A furnace that short cycles wastes a ton of energy because every time it turns on the heat exchanger has to warm up before the blower turns on and then wastes the energy cooling down after it shuts off. You also end up sending a lot more heat out the exhaust.

Heat calcs for a home are a bit more straight forward because you have a design temperature for where the home is located. Our "winter camping" has been limited to the North Cascades in October when night time lows were near freezing. Plugged into shore power a 1500 watt space heater was more than adaquate for out 24' Argosy. 1500 watts is about 5000 BTU output which would be equivalent to a 6000 BTU furnace (80% efficient).

Unless you're planning to do all of your camping north of the Artic Circle in the dead of winter with no shore power I can't imagine ever needing that much heat. And if you do your tow vehicle had better be a propane tanker

[Lothlorian]

I just put the recommended 30,000 BTU suburban furance in my 27' Overlander three weeks ago. It does not go on and off constantly. The airstream is so well insulated it keeps it from going on and off. When you first use the heater when it is cold outside it takes awhile to get all the cabinets and furniture warm. For about 30 minutes it will go on and off. Even then it is not bad. Once everything in the trailer is warm. It does not kick on and off that much. It is very quiet and efficient.

I think the engineers new what they were doing when they figured cubic airspace recommendations for that furnace. We really enjoy ours. Our house furnace cycles more then the airstreams.

Brian

[Inland RV Center, In]

Originally Posted by bhayden

Why on earth would you want 30,000 btu to heat ~200 sq ft of living space. That's 2-1/2 tons of heating capacity.

It's better to have a little more, than not enough heat.

The replacement furnace's available, in this case, is very limited, unless the owner wants to do a ton of modifications.

Andy

[bhayden]

50% isn't a little more. Most trailer furnaces are already sized to bake your eyeballs out. Massive overkill makes it that much worse. We've got a 48k BTU (4 ton) heat pump that keeps an old 1961 vintage home with massive amounts of glass and cathedral ceilings warm down to 20 degrees before the auxiliary gas furnace kicks in.

[markdoane]

I installed a 20k btu Suburban furnace in my 24' Tradewind. It run about 10 minutes three times an hour when the outside temp is below freezing.

It keeps the trailer very warm and comfortable, although no furnace will keep the outside walls warm to the touch when it's 20 degrees outside.

[ventport]

If the original furnace was 20 or 22,000 BTU's, I would go with the 19,000. The 30,000 is WAY too big, they are used to heat a 31' AS. The worst that would happen if it's below zero is the 19,000 BTU furnace would run a lot.

[pickerdd]

From reading through this thread I'm wondering if I made a mistake. I purchased a new NT34SP from Forrest River (that's the company name on the invoice) to replace the original furnace in our '71 Safari, which I'm guessing is a NT20 or NT22. Suggestions?

[Jammer]

If you come to Minnesota you'll be glad you have it. Around the Atlanta area it's more than you need.