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dznf0g · 01-11-2011, 09:58 AM

Quote:

Originally Posted by Jammer

How much electric heat do you have and where? I have 3000 watts and when temperatures are below freezing outside the propane still runs a great deal.

At this point, I only have the 1500 watt'er I used with my 22' SOB. I haven't decided whether to do something else nor what to use - hot air, oil, or some combination thereof, etc. We really can't go much more than 3000 Watts with 30A service, can we?

I do like the small 1500 watt I currently have because it's small and is useful to blow directly under the sink furnace air return port. I haven't really investigated anything else that's out there, other than reading some posts here. Suggestions?

dznf0g · 01-11-2011, 10:37 AM

Jammer,

The more I think about it, the more I think you're right about the PWM speed controller. Much simpler install. Thanks. Check this one out. What do you think?

I believe our blower motors are just under 10A, right?

QKits Electronic Kits: MX033, PWM DC Motor Speed Control Module

Jim Foster · 01-28-2011, 10:34 AM

I was asked for an "on the road" update, well, here it is.

We have been in Quartzsite AZ for a week. It has been in the low 70s during the day, but very cool at night, and by sunrise it is cold. Not the cold some if you have for sure, but nun the less, cold. I turn the furnace on, and in about two minutes the furnace is warm, so I turn the bilge blower on in the rear bath and shut the sliding doors. In about another two minutes the bath room is much warmer than the rest of the trailer. Before Lynn is finished in the bathroom, she has already turned off the blower.

So far, we really like the setup.

Jammer · 01-28-2011, 10:40 AM

Quote:

Originally Posted by dznf0g

Jammer,

The more I think about it, the more I think you're right about the PWM speed controller. Much simpler install. Thanks. Check this one out. What do you think?

I believe our blower motors are just under 10A, right?

QKits Electronic Kits: MX033, PWM DC Motor Speed Control Module

That looks like an idea kit for such an experiment.

Quote:

Originally Posted by Jim Foster

I was asked for an "on the road" update, well, here it is.

We have been in Quartzsite AZ for a week. It has been in the low 70s during the day, but very cool at night, and by sunrise it is cold. Not the cold some if you have for sure, but nun the less, cold. I turn the furnace on, and in about two minutes the furnace is warm, so I turn the bilge blower on in the rear bath and shut the sliding doors. In about another two minutes the bath room is much warmer than the rest of the trailer. Before Lynn is finished in the bathroom, she has already turned off the blower.

So far, we really like the setup.

Excellent news, Jim, thanks for the update. There is no substitute for field testing.

Jim Foster · 02-05-2011, 07:58 AM

Well gang, we have been in Texas since Tuesday. Freezing temps much of the time during the day and every night until last night here on
South Padre Island.
Electricity went out here on the island Thursday at 8 pm, and didn't come back until Friday about 3 pm. Thursday night I set the furnace thermostat to 50. The furnace cycled all night without running the batteries down. Friday morning I hooked up the Honda and got everything up again.

The fun part was the bilge blower fan supplying nice warm air to the rear bath on demand. Nice and toasty for the evening showers.

Love it, love it, love it.

Jammer · 02-11-2011, 01:31 PM

Night before last low temperatures were forecast and I decided to spend the night in my trailer to see how the heat actually works in practice.

The trailer warmed up evenly and I enjoyed a good night's sleep. It was -15 F. outside the following morning. Temperatures were still even throughout the trailer. I'm very happy with the results.

The only thing left to do is make a new floor for the closet that leaves room for the ducts. I'll post pics when it's done.

Gene · 02-12-2011, 11:18 AM

Jammer, good for you. That was quite a lot of experimentation and determination. You like a warm bedroom, we like a cold one. We should never trade trailers.

Gene

HiHoAgRV · 02-13-2011, 04:41 PM

Thank ya'll for posting your efforts and the results!

dznf0g · 03-03-2011, 11:13 AM

Thanks again Jammer, for all you experimentation. Over the winter I gathered all the parts, got the AS out of storage last week, and in about 2 hours I had my heat mod done! As I discussed above, I did get a shutter equipped vent for one of the LR vents, and now have two 4" ducts in the BR. EVEN HEAT THROUGHOUT!! Highly recommend this mod!

KYAirstream · 12-02-2012, 10:34 PM

Great thread. Just curious about pros/cons of using insulated 4" flex duct in place of the uninsulated 4" runs. Obvious con is it would require a little more space and may prevent some heating of pipes that run along the duct runs. However, I can't imagine this would be significant.

dznf0g · 12-03-2012, 06:29 AM

Quote:

Originally Posted by KYAirstream

Great thread. Just curious about pros/cons of using insulated 4" flex duct in place of the uninsulated 4" runs. Obvious con is it would require a little more space and may prevent some heating of pipes that run along the duct runs. However, I can't imagine this would be significant.

I think it depends on the routing necessary. In my case, I had to make some really sharp tight turns to get in and around the shower pan area. As a result, even with the non-insulated duct, there was some squishing or narrowing of the cross section of the duct. I think insulated, in my case, would have substantially reduced airflow.

Since I was ADDING an additional duct, I don't think it was a safety concern (overheating), but it would have defeated, to some degree, the purpose of the additional run.

Also, I do want some heat to be given off under the shower and counter to keep any potential cold spots from freezing pipes.

KYAirstream · 12-03-2012, 06:54 AM

Good point about possibly reducing airflow. What gets me is that my duct to the rear bedroom (and bath) runs through the water heater compartment, which is essentially open to the outdoors. Seems to me any warm air in the duct is likely reduced greatly on real cold nights. I suppose a better option may be to insulate that section of ductwork only, or seal up that compartment.

I've also thought about adding an extra run to the rear bedroom, but space is limited. I may try connecting a 4" duct to the old rectangular sheet metal run, which of course also runs above the outside wall of the water heater compartment, completely exposed to outdoor temps. I guess it time for sections of rigid foam and spray foam to seal things up....

Any reason why folks ran new duct for an additional run, as opposed to tapping into the old sheet metal run that goes from front to back?

dznf0g · 12-03-2012, 07:02 AM

The new units are flexible ductwork throughout, direct from the furnace plenum.

KYAirstream · 12-03-2012, 07:05 AM

I take it the new units use uninsulated 4" duct?

dznf0g · 12-03-2012, 07:09 AM

Quote:

Originally Posted by KYAirstream

I take it the new units use uninsulated 4" duct?

Yes, but I don't have any that is exposed to the outdoors in my AS. I, like you, would look into insulating the outside of those areas with something. Pics would help me to understand the two areas you are dealing with...but, I would thing maybe fiberglass with foil bubble taped around it maybe?????

Also, one run of 2" uninsulated duct down into the belly right at the furnace and run to the tank compartments. If I ever have the belly pan off, I will insulate that run and improve the insulation around the tanks, but that'll be a side job to any necessary job that may come up. Not interested in tearing into the belly ONLY to insulate.

KYAirstream · 12-03-2012, 07:25 AM

No pics here, and I'm a couple hours from the Airstream currently. When you open the access door to the water heater, if you look to the right or toward the front of the trailer, you can see where the ducts and pipes run behind the center bath shower and along the backside of the kitchen galley until they terminate under the stove at the furnace. If you look above and to the left, you can see where the rear bedroom duct travels above the water heater (under the bathroom sink) and to the rear bedroom wall.

The arrangement typically works OK on cold nights, so I haven't really worried about it. However, I began to think about how much propane I am probably wasting. I think separating the water heater compartment from the duct and adjacent plumping would help. However, the portion of the lines running immediately to and from the water heater would then be isolated from the current ducts. Hopefully there would be enough residual heat from the water heater to keep this specific section of the lines from freezing. That, or I'd improve one situation and end up compromising another.

Jammer · 12-03-2012, 10:13 AM

Quote:

Originally Posted by KYAirstream

Great thread. Just curious about pros/cons of using insulated 4" flex duct in place of the uninsulated 4" runs. Obvious con is it would require a little more space and may prevent some heating of pipes that run along the duct runs. However, I can't imagine this would be significant.

As dznf0g notes, insulated 4" flex duct doesn't fit in these trailers. There are a number of types available but they are typically at least 6" in outside diameter, and there just isn't room. The uninsulated ducts are themselves a tight fit.

At one point I tried wrapping a thinner layer of fiberglass pipe insulation around the ducts but there wasn't room to do that consistently.

Jammer · 12-03-2012, 10:22 AM

Quote:

Originally Posted by KYAirstream

Any reason why folks ran new duct for an additional run, as opposed to tapping into the old sheet metal run that goes from front to back?

The new units use uninsulated 4" flexible duct throughout and don't have a sheet metal plenum. I thought about installing such an arrangement as an upgrade, but it would be an enormous amount of work and there isn't quite enough clear area to make it workable -- the ducts have to run along the floor near the wall under the galley cabinetry and range, and then have to move towards the center of the trailer to clear the wheel wells.

In the newer trailers the ducts run entirely in interior space albeit enclosed. As such the heat loss from the ductwork only affects the distribution of heat within the trailer and doesn't cause losses to outdoors. Some of the heat loss is desirable insofar as the area containing the water pump does need to be kept warm as does the shower.

KYAirstream · 12-03-2012, 03:08 PM

Since I have access to the original sheet metal duct run that terminates in the rear bedroom, I may try attaching a 4" duct to it for extra heat. I currently have a single 4" run to the bedroom and have experienced the same issues you have described in this thread. The sheet metal run is approximately 2.5"-3" deep by a foot tall. Would it be wise to attach the 4" run at a gradual angle using an angled boot, or would a direct fit to the side of the metal run (at 90 degree angle) be alright? I thought an angled boot might help reduce static pressure. I suppose whatever I do can only help.

In my 1979 Sovereign the water pump and plumbing from the city inlet are in the bottom of a closet on the opposite side of the trailer. Airstream did leave an opening along the toe kick, so adequate heat does appear to passively get into that area. It does have quite a chill though when the closet doors are opened.

Jim Foster · 01-06-2014, 05:40 PM

Quote:

Originally Posted by Jim Foster

Well gang, we have been in Texas since Tuesday. Freezing temps much of the time during the day and every night until last night here on
South Padre Island.
Electricity went out here on the island Thursday at 8 pm, and didn't come back until Friday about 3 pm. Thursday night I set the furnace thermostat to 50. The furnace cycled all night without running the batteries down. Friday morning I hooked up the Honda and got everything up again.

The fun part was the bilge blower fan supplying nice warm air to the rear bath on demand. Nice and toasty for the evening showers.

Love it, love it, love it.

Well, It's been three years since I installed the bilge blower to move heat into the rear bath of our 1983 27' Excella. It still works well. Has never had a problem of any kind after hundreds of uses. With the furnace hot, it heats the rear bath in a couple of minutes.

Still love it.

Cheers, Jim