Solar, is it worthwhile?

[Kevin D Pem]

Radiant heat is much more difficult then just heating water and circulating it. Transfer rates, temps, and other factors make it tricky.

I get it! Kind of like putting 500 watts of solar on the roof, and expecting to heat or cool your RV! It can help but to do the job right it requires more engineering!

Point is it is just a matter of knowing the limitations, and adjusting your expectations. We aren't planning a product, just wanting to increase comfort!!!

As an example, installing 1.5 Sq. Meters of collector would be less than using a space heater for the same 5 hours of useful heat collection. It would help, but hardly do the job! Then there is the temperature difference of the heat exchanger(solar collector), that determines the actual energy collected.

But there are other advantages to covering your roof! Yes shade! That is a summer time advantage, that could help keep temperatures lower in the summer.

Thank you for stretching this conversation to a subject matter that, those that can't visualize electron flow, can follow! No matter how far off topic this seems to have strayed, one can see the physics is similar to the original topic!!!

 

[Underboss]

What company uses propane for floor heat? 99% of floor heating is electric.

 

[Kevin D Pem]

What company uses propane for floor heat? 99% of floor heating is electric.

Well Newmar may disagree with you. Isn't the oasis system floor heat?

 

[Underboss]

Newmar floor heat is electric. The Oasis is for Hot water and standard heating. I think only one manufacturer was dumb enough to do a hydro floor heat system.

 

[TheLooks]

Many homes in the North have hydronic systems with water heated by gas, wood, diesel(home heating), and solar, and coal.

 

[Underboss]

Many homes in the North have hydronic systems with water heated by gas, wood, diesel(home heating), and solar, and coal.

Well, I was under the impression that this is an rv forum and this was an rv discussion. That's what this thread was discussing but I am knowledgeable in all types of residential floor heating systems. I have built the electric radiant floor heat into my personal home when I built it. I have also built a 62 story luxury residential building where every bath on every floor had radiant electrical heating. In the properties I have been involved in personally, hydro floor heat was not a good choice. But it does have its place, but never in an rv

 

[Kevin D Pem]

Well, I was under the impression that this is an rv forum and this was an rv discussion. That's what this thread was discussing but I am knowledgeable in all types of residential floor heating systems. I have built the electric radiant floor heat into my personal home when I built it. I have also built a 62 story luxury residential building where every bath on every floor had radiant electrical heating. In the properties I have been involved in personally, hydro floor heat was not a good choice. But it does have its place, but never in an rv

So never is a strong word! Care to enlighten?? Why and what do you expect out of them?

Radiant Heating

Say goodbye to cold floors in winter. Radiant heating can be a comfortable and efficient heating choice.

www.energy.gov

I get it this sight is about disinformation, but your experience may be helpful!

 

[Underboss]

You are confusing radiant heat as only being hydronic. Radiant heat can be hydronic, or electric.

Hydronic is basically a series of tubes carrying hot water in a looped system. I would not want a series of looped water carrying tubes in a mobile vehicle. Secondly, hydronic heated floors take up more space, the thickness of the tube will raise the thickness of the floor where electric radiant heat is a thin mat with wiring inside that creates the heat. It would be impossible to put hydronic radiant heat into slide out systems. Also, with hydronic based radiant heated floors you will have a massive amount of tubing that has to be terminated into manifolds, more real estate is required for these systems. They have their place is residential and commercial but the bulk of floor heating used today in residences and apartments is electric radiant heat

 

[Kevin D Pem]

Because hydronic is basically a series of tubes carrying hot water in a looped system. I would not want a series of looped water carrying tubes in a mobile vehicle. Secondly, hydronic heated floors take up more space, the thickness of the tube will raise the thickness of the floor where electric radiant heat is a thin mat with wiring inside that creates the heat. It would be impossible to put hydronic radiant heat into slide out systems. Also, with hydronic based radiant heated floors you will have a massive amount of tubing that has to be terminated into manifolds, more real estate is required for these systems. They have their place is residential and commercial but the bulk of floor heating used today in residences and apartments is electric radiant heat

Ok! That was more useful!

However it comes down to intent, and the options available come back to hydronic! And yes I consulted a retired professional who did to their rig what I am considering for mine. He didn't consider doing the slides, and I don't have any!

 

[TheLooks]

I have done electric heat systems also, and I would consider them only usable with deep pockets or cheap electricity. No one in the NE would consider electric anything. Many fell for that scam back in the late 70's and 80's only to find that the amount of electricity used would make your meter spin off the wall. Might work fine in Fla. to take the chill off or make the floor feel warm, but not gonna work where you need some heat.

 

[TheLooks]

I have worked with radiant ceiling panels, radiant floor systems for bathrooms, and radiant under wooden floors as well as imbedded in concrete. They work the best, all of them, where you are not relying on them for your main heat and the temps are not extreme. So, middle of the country and a bit south. Heat loss studies and examinations of the building envelope are critical to making them work in more extreme climates.

 

[Underboss]

Ok! That was more useful!

However it comes down to intent, and the options available come back to hydronic! And yes I consulted a retired professional who did to their rig what I am considering for mine. He didn't consider doing the slides, and I don't have any!

How you are going to do hydronic radiant floor heat in an existing rv? Also why? Electric radiant floor heat is so much more an efficient install. Faster, easier and once installed no fear of an accidental leak. Whereas tubing can rub and break, all the manifold connections add to the possibility of leaks and the real estate required for both the tubing height, the routing of the tubing to the manifold and the heating source open up the chances of leaks exponentially.
You can do a typical rv with as many zones of electric radiant heat as you desire. That leads to better efficiency as you are not heating the bedroom floor during the day where with hydronic, additional zones create additional manifolds or diverters taking up more real estate and again adding more chances for leaking in a mobile vehicle.

 

[TheLooks]

I have to agree I don't like the idea of heated floor with water in a mobile vehicle. In fact, I don't like them at all from experience!

 

[Underboss]

I have worked with radiant ceiling panels, radiant floor systems for bathrooms, and radiant under wooden floors as well as imbedded in concrete. They work the best, all of them, where you are not relying on them for your main heat and the temps are not extreme. So, middle of the country and a bit south. Heat loss studies and examinations of the building envelope are critical to making them work in more extreme climates.

Again, you seem to be talking apples to oranges and I don't understand how you are conflating residential to an rv in an RV discussion.
Though, the 62 story building I did was residential and in NY City. These new electric systems are relatively efficient and offset the other utility costs.

 

[TheLooks]

Merely explaining I have worked with a variety of radiant systems. The OP was talking water, you changed it to electrical. I disagree with efficiency as a measure of how much they cost to operate. But NYC is another thing altogether. Not comparable to rural stand alone houses.

 

[Underboss]

Merely explaining I have worked with a variety of radiant systems. The OP was talking water, you changed it to electrical. I disagree with efficiency as a measure of how much they cost to operate. But NYC is another thing altogether. Not comparable to rural stand alone houses.

But again, we are discussing radiant floors in RVs.

 

[Kevin D Pem]

But again, we are discussing radiant floors in RVs. I was on topic. I am not sure why you seem to keep going back and discussing residential but I will bow out now because this discussion has clearly run its course

Yes efficiency is my goal! Sometimes it does a body good to see where a discussion comes from and where it's going.

From the get-go I brought up solar efficiency! So if we talk apples to whatever, we must understand where the design comes from and the intent.

The last such system I did like this, it relied on natural convection! This design will rely on a circulation pump, but will still be open to the atmosphere! As a supplemental system designed for the desert southwest, surely it may serve as a primary system, however, it will not be designed as such.

How that makes any sense is to consider my approach to life in general! Then one can almost see the logic, from another's eyes.

And to add to your "there can only be one way" view! Solar power and electrical heat stripes are not a good match! At one time RVs were conservative, but are now power hogs. My rectification with this blatant misuse of resources, can not take place within my very being!!! So it won't.

 

[RTRanger]

I love solar. I have put solar on all three RVs we’ve owned. Currently we have down sized to a Roadtrek Class B. Put 200w on the roof and 200ah LiFePo batteries. If parked in the sun the compressor fridge can run 24hrs and the batteries will be at 100% by noon. I use the Renogy DC-DC controller that will solar charge the vehicle battery when the house batteries are full. It also charges the house batteries after the vehicle battery is charged when the engine is running. Totally trouble free and everything is always fully charged. With the small loads in our little Class B we never need to plug into AC. (Unless we need AC.) It is worth it to me!

 

[Underboss]

Yes efficiency is my goal! Sometimes it does a body good to see where a discussion comes from and where it's going.

From the get-go I brought up solar efficiency! So if we talk apples to whatever, we must understand where the design comes from and the intent.

The last such system I did like this, it relied on natural convection! This design will rely on a circulation pump, but will still be open to the atmosphere! As a supplemental system designed for the desert southwest, surely it may serve as a primary system, however, it will not be designed as such.

How that makes any sense is to consider my approach to life in general! Then one can almost see the logic, from another's eyes.

And to add to your "there can only be one way" view! Solar power and electrical heat stripes are not a good match! At one time RVs were conservative, but are now power hogs. My rectification with this blatant misuse of resources, can not take place within my very being!!! So it won't.

If you have beliefs on a waste of resources thats fine. For instance I have put solar on three of my homes. Started around 2005. I do not put solar on my rv because I do not use it for boondocking and for the amount I do use it the cost is prohibitive.
As a builder and an rv owner for over 25 years, I stand by my "never in an rv" post for a wet floor heating system. You are doing it more on a principle basis and I can respect principles. I am just not sure how you will heat the water to a temperature that will heat then floors without using natural resources.
I am not sure of the pump usage of electricity but a 4' x 10' heat mat draws 3.9 amps.
You seem much more knowledgeable than me about electric usage, draw etc. How does that compare to a circulation pump? I have tried to search but most do not listed amp draw. I would imagine a 1/25 hp pump would be about 1 amp.

 

[Kevin D Pem]

If you have beliefs on a waste of resources thats fine. For instance I have put solar on three of my homes. Started around 2005. I do not put solar on my rv because I do not use it for boondocking and for the amount I do use it the cost is prohibitive.
As a builder and an rv owner for over 25 years, I stand by my "never in an rv" post for a wet floor heating system. You are doing it more on a principle basis and I can respect principles. I am just not sure how you will heat the water to a temperature that will heat then floors without using natural resources.
I am not sure of the pump usage of electricity but a 4' x 10' heat mat draws 3.9 amps.
You seem much more knowledgeable than me about electric usage, draw etc. How does that compare to a circulation pump? I have tried to search but most do not listed amp draw. I would imagine a 1/25 hp pump would be about 1 amp.

In order to keep things apples to . . . We must convert everything to watts. So .00134 hp = 1 watt, this doesn't take losses in account. That makes 1 hp = 746 watts rounded up. Keeping things to your history! BTU/h = watts * 3.412141633 .
This is where the truth gets sticky!
3.9 amps at what voltage? At 12 volts would be 46 watts or 13 btu/hrs. At 120 volts 468 watts or 137 btu/hrs. or 220 volts 858 watts or 251 btu/hrs. So we must consider what values we are discussing here.

The efficiency of pv is still well under 25% ,the efficiency of heat collectors is better than 50%.

A 250 watt pv is roughly 1.5 meters sq, and to collect 750 watts of heat the same size panel is used. Or roughly 219 btu/hr. In my circumstances I have roughly 3.5 meters not usable for pv but great for collecting heat. That gives me over 400 btu/hrs of heat to disperse within my RV! will it keep me toasty? I don't think so! Will it make me more comfortable? Most definitely!

Will I find the folly in my design? No! Because your argument has been on the back of my mind sense it's conception.

What I know is the disparity between the two technologies at my disposal, clearly gives me a direction!!!