Hot water radiant heat?

[malconium]

Originally Posted by norbert

a noble quote...actually you unknownly will be achieving what is known as a 2 stage system if you keep your forced air system....cost factors usually dictate only a one stage system...given that cost seems to be no object.... i applaud you and wish you well in your endeavor...
norby

As a matter of fact my AS is in need of replacements for most everything. I need to replace the wather heater, water pump and the heating system anyway. That is part of the reason that I am taking a closer look at my options. If I go with radiant heat my intention is to not replace the forced air heater at all. I wouldn't mind recovering the space under the kitchen sink.

Malcolm

[74Argosy24MH]

Originally Posted by malconium

I don't actually have to switch between potable and heating water......So a 3 way valve is not needed.

Ah, but it is. You need to get a pencil and paper and draw this out.

Normal operation takes the water from the freshwater tank, to the pump, then splits to feed the water heater and cold water systems.

Your system is doing nothing more than recirculating water.

How are going to get water to the cold taps if you don't draw it from the tank? The only way to do that and recirculate hot water with the same pump is a 3 way valve.

John

[Leipper]

Malcom, thanks for the attempt to clarify between maximums and average needs.

"the radiant heating system is an extremely efficient means of heating people and that only about 25 BTU's per square foot of floor panel would be consumed from the water heater."

Where I am still puzzled, though, is that there is such a discrepency between this rate and that typically found in RV heating systems. Even catalytic heaters, another form of radiant heat, produce significantly more heat and they are not considered suitable for entire RV heating.

I do think you will need an additional pump, though. But it still sounds like an interesting experiment and I hope you will continue to share what you find out with us.

[malconium]

Mark made a good point about the location of the main water pump in an RV which I had not entirely thought out. The more I think about it the way to go would be to have a second pump just for the hot water heating. With a second pump I would not expect to need a valve. When the pump is off the hot water will not be moving around the heating system. I suppose it would be a good idea to consider shutting off the heating system from the rest of the water system during the warm months or at least circulating some water through them from time to time to keep the water there from stagnating.

The 300 feet of tubing is what comes in a roll. The insulated floor panels actually take 2' per square foot of panel. The tubing is deployed on 6" centers.

Is it strictly speaking necessary to drain all the water out of the plumbing? It seems to me that if most of the water is out the remaing water would freeze and expand in the path of least resistance - namely into the area not filled with water. Also I should note that I live in Portland, Oregon where the problems with pipe freezing is not as bad as some places I could think of.

A couple of questions occur to me as follows:

1.) Is there any reason I couldn't leave my water heater and floor heat turned on when I am driving if it is really cold outside? That would relieve the potential problem of the thermal lag time if I left the heat on at some lower maintenance level. If I could do that I might very well be tempted to install the radiant heat tubing under the plywood floor instead of above in the insulated panels. It turns out that this approach would actually be a good deal less expensive (a savings of perhaps $300 or $400). Instead of using the insulated panels you use strips of aluminum that are 5" wide and grooved to snap onto the PEX tubing. The tubing is laced around under the floor and the aluminum strips are snapped on from below and stapled to the bottom of the floor. Relective foil insulation is commonly used below the tubing for this type of installation - which is what I had intended to do anyway. Heat under the floor would also take care of the plumbing and holding tanks pretty well I would think. I probably would deploy the heating over the whole floor area as well.

2.) Is there any reason that I could not move my water heater to the location where my forced air heater used to be? The heater used to be on the curbside under the kitchen sink. Besides the obvious fact that I would have a big hole to fill where the water heater used to be is there any other reason that this would not work? This would get the noise away from the bedroom - yes my water heater location is under the bed too.

Malcolm

[74Argosy24MH]

Originally Posted by malconium

Is it strictly speaking necessary to drain all the water out of the plumbing?
1.) Is there any reason I couldn't leave my water heater and floor heat turned on when I am driving if it is really cold outside?
2.) Is there any reason that I could not move my water heater to the location where my forced air heater used to be?

Draining plumbing-absolutely. You are talking about a lot of water that could be left in the tubing. If you get the trailer absolutely level it would be just a small amount laying in the bottom. A slight angle will put it all to the low end and leave no room for expansion.

1.)The belly pan is not airtight, you will probably affect the flame with the air flow because of the speed of the trailer.

2.) Move the water and gas, make a new hole, patch the old. Not that big a deal with a little ability.

John