Radiant Hydronic Heating and More

[paulnack]

More... the whole plumbing system actually. Currently it exists only on paper and before I birth it into the world, I'm hoping for some constructive criticism from those who have actually constructed.

Plans are for fully integrated system, sans black tank.
-100 gal fresh tank, 70 gal grey (the biggest I could fit in basement)
-Dual tankless heaters, elec for on-grid, propane for off-grid
-Radiant in-floor hyrdonic heating
The rest seems to be standard skoolie fare...

The radiant heating gives me the most pause. Has anyone done this with a tankless heater? Can I use a branch off the fresh water, or do I need a separate closed system with a heat exchanger?

I am a complete novice with plumbing... I've attached a diagram of my best attempt, but hoping someone more knowledgeable can pick it apart. Many thanks in advance!

[Hengy]

I'm a noob on Skoolie Conversions, but looking at your drawing, I have a concern. For your radiant heating system, you need a couple of things to make sure that you don't build up pressure in the closed loop system.
1. Small expansion tank teed off of the lines running to your hydronic system. This will allow expansion of the hot water in and contraction of the cold water in the system.
2. A pressure relief valve. If, for some reason, the pressure gets too high in your system, this valve allows controlled release of water.


Since you already are thinking 2 water heaters, why don't you just do 2 LP heaters. One for the heating system and one for the hot water system to keep things separate.


Mike in Pittsburgh, PA

[o1marc]

The floor system should be a self contained loop and not tied into the house water system. I have separate tankless heaters for both. Were you talking about having to tanks, one electric and one propane? You lost me there, don't know of any combo units like that. Why would the propane one not be sufficient for all use.

[paulnack]

Originally Posted by Hengy

I'm a noob on Skoolie Conversions, but looking at your drawing, I have a concern. For your radiant heating system, you need a couple of things to make sure that you don't build up pressure in the closed loop system.
1. Small expansion tank teed off of the lines running to your hydronic system. This will allow expansion of the hot water in and contraction of the cold water in the system.
2. A pressure relief valve. If, for some reason, the pressure gets too high in your system, this valve allows controlled release of water.
Since you already are thinking 2 water heaters, why don't you just do 2 LP heaters. One for the heating system and one for the hot water system to keep things separate.
Mike in Pittsburgh, PA

Good point, pressure increase is proportional to temperature increase. So an expansion valve/tank will be necessary. Thank you for bringing this to my attention.
The reason for dual heaters it to be able to use the 2 energy sources. Electric when I'm hooked up at a campsite, propane when I'm off grid. Electric water heating to too energy hungry to do with batteries. And I want to be able to park somewhere for extended periods without chugging through propane bottles and having to run for refills.

Originally Posted by o1marc

The floor system should be a self contained loop and not tied into the house water system. I have separate tankless heaters for both. Were you talking about having to tanks, one electric and one propane? You lost me there, don't know of any combo units like that. Why would the propane one not be sufficient for all use.

Hey, see the paragraph above about the dual energy source. I wasnt thinking a single "dual-fuel" unit, but rather 2 tankless units (havent decided series or parallel). Although I would love one if it exists.
Can you please explain why I can't branch the radiant system off the house water? I've read this elsewhere, but haven't seen reasoning why not.
How has your experience been running the radiant off a tankless? I've read that the often off/on operation of maintaining the constant temp will drastically reduce a tankless heaters lifespan. Most units aren't warrantied for this type of use for that reason.

[Brain's 97 Diesel]

Heated house water (sink, shower, washing machine, dishwasher) all use the water as a direct heated item in a water heater, weather tank or tank-less and regardless of fuel source. Fresh water in from source - fresh heated water out to use.

Liquids (not water, but rather coolant, antifreeze, oil, something with a VERY low freezing point) used for a heat source (radiator, radiant floor, or heater core with a blower) usually use some form of anti freeze type liquid that is heated and circulated to provide warmth to a space. This usually involves a boiler (in which the liquid is heated), thermostats (like in a car to allow the heated fluid to pass or stop), pressure relief valve or valves (so the system doesn't explode from too much pressure), an expansion tank (to allow the expansion and contraction of fluids), a manifold to direct where it is to go (you may have more than one area or loop), and a circulation pump (to push or pull the fluid through the system so it won't have hot or cold spots in the system).

The reason for two (2) different systems is cross contamination (you don't want to drink antifreeze). Also the heater will need to cycle all night according to the temperature set at the thermostat(s), but the water heater will only need to cycle when needed for tank-less or as the holding tanks minimum temperature is reached for a tank type.

For your water heater why not go with a 5, 6, or 10 gallon dual fuel (propane and 110V electric) RV tank water heater. They heat up quickly and hold the contents at temperature for several hours. The one in our RV is 5 or 6 gallons, we run it on propane when not hooked up to electric and turn it on 15-30 minutes before we need it, and turn it off when we are done with it.

[wrenchtech]

https://www.radiantec.com/

This site has lots of information about DIY hydronic heating using readily available high-end water heaters and tankless water heater‘s. One of the things they stress is that in most cases tankless heaters used for hydronic heating will void the warranty. They have some design recommendations that are designed to work with the manufacturers requirements. It’s not totally easy to find the info on their website. Look carefully at the navigation bar menu at the top of the homepage.

I am studying this as well and seriously considering using a hydronic solution for my heating purposes.

[cadillackid]

my new Navien Hot water heater at home can be used for Hydronic Heating... it has a DHW loop feature and navien approves of it being used for space heating... there are also combi-boilers which can have 2 temperatures of water depending on their internal heat exchangers..

[JackE]

Originally Posted by o1marc

The floor system should be a self contained loop and not tied into the house water system. I have separate tankless heaters for both. Were you talking about having to tanks, one electric and one propane? You lost me there, don't know of any combo units like that. Why would the propane one not be sufficient for all use.

Do you have a post on how you did your floor system? I'm very interested in what you did, how you did it, and what parts you used. I have read some info on using a tankless heater for this, but all of it refers to house, not a mobile application. Do you feel like this provides adequate heat for your bus?

[WIbluebird]

Originally Posted by JackE

Do you have a post on how you did your floor system? I'm very interested in what you did, how you did it, and what parts you used. I have read some info on using a tankless heater for this, but all of it refers to house, not a mobile application. Do you feel like this provides adequate heat for your bus?

He's banned. Don't expect a reply anytime soon.

[JackE]

Originally Posted by WIbluebird

He's banned. Don't expect a reply anytime soon.

Dang, what does a guy with almost 9000 posts do to get banned?

[WIbluebird]

Originally Posted by JackE

Dang, what does a guy with almost 9000 posts do to get banned?

Sold a bus to a forum member and claimed that it had features that it didn't actually have.

[Booyah45828]

Originally Posted by JackE

Dang, what does a guy with almost 9000 posts do to get banned?

Originally Posted by WIbluebird

Sold a bus to a forum member and claimed that it had features that it didn't actually have.

There was more to it. How he presented himself and then handled the whole deal was the issue.

You can't put yourself out there as an expert, mis-state several options on a bus you were illegally selling, scam some people out of their money, and then not refund said money because you purchased guns with it.

[JackE]

Originally Posted by WIbluebird

Sold a bus to a forum member and claimed that it had features that it didn't actually have.

I actually just found the lengthy thread about that whole debacle. What a mess! After reading what I have about him, I don't think I would take any advice from him anyway. People with a lack of integrity really frost my goat!

[paulnack]

Originally Posted by Brain's 97 Diesel

...
Liquids (not water, but rather coolant, antifreeze, oil, something with a VERY low freezing point) used for a heat source (radiator, radiant floor, or heater core with a blower) usually use some form of anti freeze type liquid that is heated and circulated to provide warmth to a space.
...
The reason for two (2) different systems is cross contamination (you don't want to drink antifreeze). Also the heater will need to cycle all night according to the temperature set at the thermostat(s), but the water heater will only need to cycle when needed for tank-less or as the holding tanks minimum temperature is reached for a tank type.

For your water heater why not go with a 5, 6, or 10 gallon dual fuel (propane and 110V electric) RV tank water heater. They heat up quickly and hold the contents at temperature for several hours. The one in our RV is 5 or 6 gallons, we run it on propane when not hooked up to electric and turn it on 15-30 minutes before we need it, and turn it off when we are done with it.

Brian, a few reasons I don't want a small tanked water heater: I don't want to need to remember to turn it off when not in use, and I don't want to rush my showers for fear of them turning cold. I will be full timing and want my lifestyle to be as close to a brick-and-mortar home as possible.

As for the plumbing: Anti-freeze is not necessary. In fact, it reduces the heat capacity of the water. If using plain water I can have a branch off my household water, the trick is in plumbing it correctly for all types of use. I will need an expansion valve with an open-pressure greater than that of my pump, but less than the max pressure of my piping. And using a tankless heater, I think I will rig my thermostat to control the circulation pump. In this case the pump kicks on when ambient temp is low and the flowing water automatically activates the tankless heater, and when the desired ambient temp is reached pump kicks off/ flow stops/ heater turns off.

Originally Posted by wrenchtech

https://www.radiantec.com/
This site has lots of information about DIY hydronic heating using readily available high-end water heaters and tankless water heater‘s. One of the things they stress is that in most cases tankless heaters used for hydronic heating will void the warranty.
...
I am studying this as well and seriously considering using a hydronic solution for my heating purposes.

Wrench, that's a hot tip thank you for sharing that resource. Do you have a link to their literature specifically about tankless heating?
I'll keep you in mind as I work through the R&D of this system. Let's continue to share notes.

[cadillackid]

Originally Posted by Booyah45828

There was more to it. How he presented himself and then handled the whole deal was the issue.

You can't put yourself out there as an expert, mis-state several options on a bus you were illegally selling, scam some people out of their money, and then not refund said money because you purchased guns with it.

should mention that he sold someone a BROKEN bus.. that he himself noted an Issue with when he drove it home to his place before selling it as a SOLIDLY WORKING bus..

[wrenchtech]

Originally Posted by paulnack

Brian, a few reasons I don't want a small tanked water heater: I don't want to need to remember to turn it off when not in use, and I don't want to rush my showers for fear of them turning cold. I will be full timing and want my lifestyle to be as close to a brick-and-mortar home as possible.

As for the plumbing: Anti-freeze is not necessary. In fact, it reduces the heat capacity of the water. If using plain water I can have a branch off my household water, the trick is in plumbing it correctly for all types of use. I will need an expansion valve with an open-pressure greater than that of my pump, but less than the max pressure of my piping. And using a tankless heater, I think I will rig my thermostat to control the circulation pump. In this case the pump kicks on when ambient temp is low and the flowing water automatically activates the tankless heater, and when the desired ambient temp is reached pump kicks off/ flow stops/ heater turns off.



Wrench, that's a hot tip thank you for sharing that resource. Do you have a link to their literature specifically about tankless heating?
I'll keep you in mind as I work through the R&D of this system. Let's continue to share notes.

https://www.radiantec.com/installati...o-it-yourself/

https://www.radiantec.com/installati...uction-manual/

https://www.radiantec.com/installati...direct-system/

This should give you something interesting to read. Beware though, their website doesn’t work well at all devices.