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2airishuman · 11-24-2010, 04:03 PM

Quote:

Originally Posted by w7ts

My experience is that very little heat and not much airflow makes it to the bathroom...

the flow 2 my johnny is toasty...

easily the 30 degrees warmer that jammer notes above.

given the shower space is warmed via the ducts leaking and hot water,

i could get by without direct head heating, pretty easily.

the insides of these streams are very different at 20 with wind,

or when it's 10 and colder outside.

since all the bits contract (shrinkage!) every gap gets gapEEr, especially the entry door.

and a LOT of air comes in via the fridge backsides/install, the drawer underneath becomes a wine chiller.

i could tell reliably when the outside temps hit zero in the old moho...

the shower trap wasn't insulated and would freeze, filling the pan with bath water.

cheers
2air'

Jammer · 11-24-2010, 04:24 PM

Would work but since the bathroom also lacks heat I doubt if it would help much.

[eta: crossposted with 2air] A factor to consider is that the bulkhead forward of the 'fridge is a source of heat loss since the 'fridge compartment is vented to outside. Adjoining areas, the dinette and the wall next to the head in my traylah, are cooled as a result.

Adding heat IN the bathroom might solve much of the problem but there is no room to do so in a 30' (head on streetside and shower on curbside). The places to do it are taken up by wheelwells, lav sink, and the water heater.

There may be a third possibility that we have not counted upon :-) which is that we could run an additional flexible duct back from the Atwood to the bedroom. It could replace one of the outlets into the living room area or be a fifth connection through the bottom of the furnace.

2airishuman · 11-24-2010, 05:07 PM

is there no duct near the john under the sink?

yep, floor plan matters.

and the split bath is an issue at the shower,

that' how the oldmoho was too and shower stall was like a meat locker when cold out.

on the 34 curbside is entry door/dinette/fridge and long closet with only the water pump as plumbing bits.

street side is galley and full bath and furnace and water heater and all the ducting and plumbing...

except for the 1 lame duct that passes UNDER the subfloor, along with the water pump feeds/returns.

these hvac/plumbing layouts are rubrics from another dimension.

the one redeeming factor with the basic 34 is they've been tweaking the SAME floorplan 4 a really long time.

cheers
2air'

Jammer · 11-24-2010, 05:34 PM

The layout is:
curbside - galley sink with furnace below, range, closet, shower
streetside - cabinet, dinette, fridge, head, lav sink with water heater below

Ductwork includes
- two outlets inches away from the range facing forward across the entry door towards the gaucho
- one duct with an outlet just forward of the shower. The interior of the closet extends about 10" aft of the closet door into the bathroom area and the outlet is in the wall between the closet and the bathroom.
- one duct leading under the shower to the bedroom.

A degree of heat in the shower enclosure is provided by the duct to the bedroom.

I believe that both the bathroom and bedroom ducts have small side ducts T'ed off them with little 1.5" tendrils extending down into the tank area and the space where the water lines cross under the trailer to reach the head and lav.

Overall the floorplan is highly functional. The only thing I would change is I would make the cabinet area forward of the dinette a few inches smaller to accommodate a slightly larger dinette.

Jammer · 11-27-2010, 10:16 AM

One of the outlets from the furnace is a smaller (1.5") duct going to the tank area. I can see that it would be possible to replace this with a larger duct going to the bedroom, and a T, so that air is still sent to the tank area. I may explore this further. I think the largest problem area is getting the duct across the water pump area below the closet floor, since that space is now somewhat crowded with the addition of the wall can for the electric heat.

Gene · 11-27-2010, 11:11 AM

Adjustable registers are available. They come in several colors that may better match the interior of your Airstream. They turn to direct flow just like the OEM registers, but also can be opened and closed. They are not of particularly high quality, but neither are the OEM ones. They are made by the same manufacturer. I think the ones with the adjustable flow are a dollar or two more than the OEM ones.

I replaced 3 of the factory ones with ones made for Winnebagos because of the better color match and the ability to adjust air flow. Unlike Jammer, we want the bedroom to be cooler, so I just shut off the bedroom. I did not notice any significant increase in air flow from the other registers, but if there's a T off to the tanks, maybe the bedroom air is going there, not a bad thing.

You could close down the living area registers part way to increase flow to the bedroom. I don't know whether shutting down one register will negatively affect the furnace. If there are T's from the bedroom and bathroom ducts, it may be a small change.

Our thermostat is in the bedroom so when the bedroom is cool, the rest of the trailer can get too warm. I would prefer the thermostat to be in the living area.

I believe this is the vendor where I got the registers: Winnebago Parts - Official Winnebago Parts and Accessories Catalog

Gene

Jammer · 12-08-2010, 02:01 PM

Looks like the furnace ducts are 4" (not 3" as I stated upthread).

There are cheaper sources for ductwork. Amazon has a couple of grades. Here's the better one, at $3 a foot:

Amazon.com: M-Kc Thermaflex Flexible Hvac Duct - 4 Inch Diameter R4.2: Home Improvement

I'm thinking I may try using some of that. It should help with both the noise and the heat distribution.

Jammer · 12-08-2010, 02:24 PM

I note that the static pressure specification is 0.1" WC at the duct and .25" in the casing.

Atwood recommends flexible duct have a temperature rating of 250 degrees continuous, for short ducts less than 9" in length (the galley ducts would be in this category), and 200 degrees continuous for longer runs. However, the high limit is set at 190 degrees.

Jim Foster · 12-08-2010, 02:38 PM

Quote:

Originally Posted by Aerowood

You could put an inline fan in the duct going aft to boost the flow They are available in a couple different sizes.

yellowTAIL™ 3” Blower - SHURflo

What a great idea. A bilge blower. Our 27' Excella has the furnace forward beneath the stove by the entry door. It's a long way to the rear bath, and it would be nice to sometimes have more heat there. One of these blowers can be installed somewhere convenient in the hose to the bath with it's own switch to be used only when extra heat is needed in the bath.

I'm looking into this.

Jammer · 12-08-2010, 02:49 PM

There are two problems with the bilge blowers.

First of all, they draw 5.5 amps (for the 4" one).

Second, they're loud.

Nonetheless, something to consider.

Jim Foster · 12-08-2010, 02:59 PM

Quote:

Originally Posted by Jammer

There are two problems with the bilge blowers.

First of all, they draw 5.5 amps (for the 4" one).

Second, they're loud.

Nonetheless, something to consider.

In our trailer it will be located under the curb side twin, or in the bottom of the rear curb side closet. I doubt that it will be too loud if located under the bed, but even so, we will only run it for a few minutes before showering to get the bath nice and toasty.

Found them also made by Rule and Atwater on line from various suppliers starting at about $25 plus shipping for the 4".

If I do this, I will certainly post back and let folks know how it works out.

Jammer · 12-08-2010, 03:00 PM

Also, they may not withstand the heat. The datasheet does not specify a maximum temperature, and the duct may easily reach 170 degrees.

http://www.ittflowcontrol.com/files/itemdoc12671.pdf

Jim Foster · 12-08-2010, 03:09 PM

Another thought would be to turn on the fan in the little round roof vent in the bath, and close the door. With the window closed, that increase the flow through the furnace duct near the floor and warm the bath.

I think I'll try that first.

rock60 · 12-08-2010, 03:59 PM

i had a 84 30p avion with twin beds and rear bath. the po owner must needed more heat in the bath because the bath door when open it blocked the heat vent that was at the bottom of tub right behind the door when it was left open. so what he did was ad another vent in the center of the tub at the bottom of tub. that put two vents in the bath. stayed the same temp as the rest of trailer. avions have the same lay out as airstreams.

richinny · 12-08-2010, 06:14 PM

since it headed to the 40's at night this week i thought i'd test using the computer fan in the bedroom outlet.

first i removed the outlet. the square fan did not fit in the round duct so i snapped the ends off the fan and made it round. it fit snugly into the outlet. i temporarily fed the wires through the outlet to test it.
i used a cheater cord plugged into one of the 12v accessory outlets.

using the infrared thermometer i bought today i had the following results:
outside temp = 55 degrees
outlet temp without fan = 105 degrees
outlet temp with fan = 117 degrees

with the fan on i could actually FEEL the warm air 1 foot away from the outlet. without the fan i can barely feel if the heat is on.

the fan without the heat being on. hums quite a bit in the enclosure where the outlet is located at the foot of the bed. wiring it to the blower fan would be a must. using a heat sensor might run the fan in the summer heat. with the blower fan on you can't hear the outlet fan.

richinny · 12-08-2010, 06:17 PM

pictures

dznf0g · 12-08-2010, 07:10 PM

Ricky,

Is that a 4" computer fan?

richinny · 12-08-2010, 07:17 PM

yes. i like to remove them from old computer power supplies. :-)

dznf0g · 12-08-2010, 07:30 PM

Quote:

Originally Posted by richinny

yes. i like to remove them from old computer power supplies. :-)

Radio Shack carries them for about $20. I use one for the fridge compartment controlled by a home furnace blower thermal switch slipped inside the chimney sleeve.

There's got to be an automatic way of turning this duct application short of running a wire all the way up to the furnace blower circuit.

Actually, on my AS that may not be too hard, now that I think about it, using a fish wire. Thanks for the idea!

Jim Foster · 12-08-2010, 07:40 PM

I'm not sure I would want the fan supplying the bath to be connected to the furnace fan. I think I would prefer to have it on a separate circuit to run only when extra heat is wanted in the bath. Really don't need extra heat in the bath except for shower time.

Just my thought.