Reply
 
Thread Tools Display Modes
 
Old 08-14-2019, 04:35 PM   #1
Skoolie
 
Join Date: Mar 2019
Location: Norfolk, VA
Posts: 121
Year: 2003
Coachwork: International
Chassis: Integrated CE S
Engine: DT466
Hydronic floor heating, 2x 5kW burners

I've been keeping some feelers out for coolant heaters since starting, just so I'm familiar with it when the time comes to get one. Across my radar came a guy selling used Espar heaters. He doesn't know the specifics, but he and I figured that they are 5kW heaters.

My bus is a full 35' and we will insulate well, but 5kW may not be enough if we encounter harsher weather, nearing 0F, which we intend to do eventually. My thought is to split up the hydronics in the interior into 2 sections, and get 2 of those heaters and run each section off of each heater.

Does anyone have opinions of this? What kW (or BTU) coolant heating system are you using and how well does it work for you in the cold climates?
__________________
Build thread: http://www.skoolie.net/forums/f11/bus-down-by-the-river-26371.html
inhof009 is offline   Reply With Quote
Old 08-14-2019, 09:05 PM   #2
Bus Nut
 
Join Date: Nov 2016
Posts: 871
The chinese knockoffs are dirt cheap and work well, just buy Espar parts as replacements needed or stock up on spares from the get go.

Cleaning them out with kero once in a while apparently helps.

The biggest factor in efficiency is how tight your insulation envelope and how thick for R-value, especially up top. 4-6" is not overboard for snow camping, ski bumming etc.

Multiple smaller spaces easier than all one big one.

I would go for low-down heat exchangers and computer-style silent circulating fans, rather than actually heating the floor. If **also** doing the latter, focus on key spot areas open to traffic.

To many designs end up heating kitchen cabinets, under-bed storage etc.
john61ct is offline   Reply With Quote
Old 08-15-2019, 01:19 AM   #3
Almost There
 
Join Date: Dec 2018
Location: Mt Vernon, WA
Posts: 96
Year: 1996
Coachwork: Bluebird
Chassis: G30 Bluebird Microbird
Engine: 1995 Chevrolet 350
ďIt dependsĒ
Iím designing a hydronic system for my bus also. I assembled a diy hydronic heater in my old Motorhome that works well. Walking on the warm floor is great! How diy and Rube Goldberg do you want to get? I usually avoid anything with circuit boards so built my own system that I can fix myself for my off grid boondocking way of life
As far as btu it doesnít matter to me because I always have several heating systems. I turn on both if necessary. The really cold snaps are usually short where I live. Itís mild near Seattle. The diy hydronic is great most of the time.
Another way is I use the catalytic heater briefly to heat it up from cold when I return from work, etc, then the vented floor heat system takes over and keeps it perfect. And minimal moisture as itís vented.
I made my own heater by finding the heat exchanger core of a Bosch on-demand propane water heater on eBay or at a scrap yard. I set this on a big two burner cast iron propane stove. Placed a stainless steel box over it. Cut a 4Ē hole in the top for a 4Ē chimney. Cut a rectangular hole in the side to reach in and light it and adjust the flame. I can run one burner or two. The big cast iron burners have lots of holes. I adjust down low it so there is only a small bright blue flame, no yellow. It will run for 3-5 days on a small 20 lb propane tank. I carefully designed it so the exhaust is just warm enough to go out the chimney but not hot and wasting fuel.
Also torched two small holes in the box for the fittings for the fluid. I have a 10 gallon buffer tank above this pseudo boiler and a thermostatic mixing valve in the system. These are pretty cool valves to design systems with. I can use the valve and a fan coil to dump the stored heat from the tank quickly when I get back from work. It worked until I forgot and I hadnt put the antifreeze in it or drained it properly and froze my nice valve and the heat exchanger. I soldered up the Bosch heat exchanger. But the Honeywell thermostatic mixing valve needs a rebuild kit.
Be sure thereís no way to have pressure build up and Kaboom! Rule of thumb is itís a code violation to place any valve between the heated source and the pop-off valve. Someone may close the valve! A clear path always needs to be in place.
There are lots of other safety strategies. A dual snap switch running power to a propane shut off solenoid valve is very basic. Snap switches fail open if they fail thus shutting down the propane supply. They can fail closed but I have heard its very rare. Donít let them get corroded.
For a large bus several heating zones makes sense. Rule of thumb is to not go over 300 feet in a zone with 1/2Ē PEX. In a bus a zone is usually between 100-150 feet so not a issue. A full size bus in one zone could would close to or over 300 feet so donít do that. Though the delta T (return fluid temp compared to outgoing fluid temp) is better with longer zones so donít make them too short either. Depends how good your thermal heat transfer in the floor, fluid temperatures, etc. Low temp systems, under 100 degrees are most efficient and easy on the materials with less expansion-contraction and stresses.
Use common sense and take your time and it should work good. Minimize sharp turns in the tubing. Especially near the pump. Avoid high and low spots in tubing. Use air eliminator at the highest place and drain at the lowest.
Place the pump in the cold return leg not the hot leg. Place expansion tank near the pump after the pump.
Best is to read Seigenthalers Solar or Modern Hydronic Heating books if your serious about it.
Good luck
Doktari is offline   Reply With Quote
Old 08-15-2019, 01:25 AM   #4
Almost There
 
Join Date: Dec 2018
Location: Mt Vernon, WA
Posts: 96
Year: 1996
Coachwork: Bluebird
Chassis: G30 Bluebird Microbird
Engine: 1995 Chevrolet 350
I will add Iíve been trying radiant floor heat partly because Iím not heating all the air molecules so in theory the insulation isnít as much of a factor as with forced air. And I like the feel of cool air temperature and warm radiant heat at the same time. And theoretical fuel savings. But of course adequate insulation is good to buffer from temperature fluctuations, wind chill, etc.
Doktari is offline   Reply With Quote
Old 08-15-2019, 08:12 AM   #5
Skoolie
 
Join Date: Mar 2019
Location: Norfolk, VA
Posts: 121
Year: 2003
Coachwork: International
Chassis: Integrated CE S
Engine: DT466
Quote:
Originally Posted by john61ct View Post
The chinese knockoffs are dirt cheap and work well, just buy Espar parts as replacements needed or stock up on spares from the get go.

Cleaning them out with kero once in a while apparently helps.

The biggest factor in efficiency is how tight your insulation envelope and how thick for R-value, especially up top. 4-6" is not overboard for snow camping, ski bumming etc.

Multiple smaller spaces easier than all one big one.

I would go for low-down heat exchangers and computer-style silent circulating fans, rather than actually heating the floor. If **also** doing the latter, focus on key spot areas open to traffic.

To many designs end up heating kitchen cabinets, under-bed storage etc.
John,

Thanks for the response! You mentioned chinese knockoff coolant heaters, what's your experience with them? I was looking reallllly hard at a 10kW Drivworld heater I found online for $400. That's cheaper than one of the individual heaters this guy is selling, and twice as powerful. I just haven't found someone yet who has used one of these coolant heaters and can tell me how theirs is working.

I intend to maximize insulation, but that'll wind up being about 2" all around to prevent losing too much interior space.

I do intend to do both in-floor heating and running a few coils behind computer fans.
__________________
Build thread: http://www.skoolie.net/forums/f11/bus-down-by-the-river-26371.html
inhof009 is offline   Reply With Quote
Old 08-15-2019, 08:18 AM   #6
Skoolie
 
Join Date: Mar 2019
Location: Norfolk, VA
Posts: 121
Year: 2003
Coachwork: International
Chassis: Integrated CE S
Engine: DT466
Quote:
Originally Posted by Doktari View Post
ďIt dependsĒ
Iím designing a hydronic system for my bus also. I assembled a diy hydronic heater in my old Motorhome that works well. Walking on the warm floor is great! How diy and Rube Goldberg do you want to get? I usually avoid anything with circuit boards so built my own system that I can fix myself for my off grid boondocking way of life
As far as btu it doesnít matter to me because I always have several heating systems. I turn on both if necessary. The really cold snaps are usually short where I live. Itís mild near Seattle. The diy hydronic is great most of the time.
Another way is I use the catalytic heater briefly to heat it up from cold when I return from work, etc, then the vented floor heat system takes over and keeps it perfect. And minimal moisture as itís vented.
I made my own heater by finding the heat exchanger core of a Bosch on-demand propane water heater on eBay or at a scrap yard. I set this on a big two burner cast iron propane stove. Placed a stainless steel box over it. Cut a 4Ē hole in the top for a 4Ē chimney. Cut a rectangular hole in the side to reach in and light it and adjust the flame. I can run one burner or two. The big cast iron burners have lots of holes. I adjust down low it so there is only a small bright blue flame, no yellow. It will run for 3-5 days on a small 20 lb propane tank. I carefully designed it so the exhaust is just warm enough to go out the chimney but not hot and wasting fuel.
Also torched two small holes in the box for the fittings for the fluid. I have a 10 gallon buffer tank above this pseudo boiler and a thermostatic mixing valve in the system. These are pretty cool valves to design systems with. I can use the valve and a fan coil to dump the stored heat from the tank quickly when I get back from work. It worked until I forgot and I hadnt put the antifreeze in it or drained it properly and froze my nice valve and the heat exchanger. I soldered up the Bosch heat exchanger. But the Honeywell thermostatic mixing valve needs a rebuild kit.
Be sure thereís no way to have pressure build up and Kaboom! Rule of thumb is itís a code violation to place any valve between the heated source and the pop-off valve. Someone may close the valve! A clear path always needs to be in place.
There are lots of other safety strategies. A dual snap switch running power to a propane shut off solenoid valve is very basic. Snap switches fail open if they fail thus shutting down the propane supply. They can fail closed but I have heard its very rare. Donít let them get corroded.
For a large bus several heating zones makes sense. Rule of thumb is to not go over 300 feet in a zone with 1/2Ē PEX. In a bus a zone is usually between 100-150 feet so not a issue. A full size bus in one zone could would close to or over 300 feet so donít do that. Though the delta T (return fluid temp compared to outgoing fluid temp) is better with longer zones so donít make them too short either. Depends how good your thermal heat transfer in the floor, fluid temperatures, etc. Low temp systems, under 100 degrees are most efficient and easy on the materials with less expansion-contraction and stresses.
Use common sense and take your time and it should work good. Minimize sharp turns in the tubing. Especially near the pump. Avoid high and low spots in tubing. Use air eliminator at the highest place and drain at the lowest.
Place the pump in the cold return leg not the hot leg. Place expansion tank near the pump after the pump.
Best is to read Seigenthalers Solar or Modern Hydronic Heating books if your serious about it.
Good luck
Doktari,

So if I understand your design properly, you're basically using a propane stove rigged to heat your water? Quite clever! Do you ever use this design while driving? My only concern is that I want to be able to use the heating while driving if the engine isn't providing enough heat, and I don't like the idea of running propane anything while driving.

I'm curious about your suggestion of the pump at the cold leg. The heaters I'm looking at have a pump included, and I was thinking of cannibalizing the coolant pump from the rear heaters to run the in-floor system, but I was thinking of putting it on the hot end. Why do you suggest the cold end?
__________________
Build thread: http://www.skoolie.net/forums/f11/bus-down-by-the-river-26371.html
inhof009 is offline   Reply With Quote
Old 08-15-2019, 12:34 PM   #7
Bus Nut
 
Join Date: Nov 2016
Posts: 871
Yes Drivworld, no direct experience, but some threads over at sprinter-source forum, lots of members use the forced-air versions.

Heating off anything but engine waste while driving will be very wasteful, hard to get a perfect insulation envelope and the in/exfiltration is huge at speed.

You do not want to keep everything warm all the time, basically unaffordable.

Have you considered infrared panels maybe wave catalytic? Heat the body not the air, very quick startup comfort, give time to get the interior warmed up from the forced-air or hydronic.

Hydronics are not that, take a very long time to get the interior temps comfortable.
john61ct is offline   Reply With Quote
Old 08-15-2019, 02:52 PM   #8
Almost There
 
Join Date: Dec 2018
Location: Mt Vernon, WA
Posts: 96
Year: 1996
Coachwork: Bluebird
Chassis: G30 Bluebird Microbird
Engine: 1995 Chevrolet 350
Quote:
Originally Posted by inhof009 View Post
Doktari,

So if I understand your design properly, you're basically using a propane stove rigged to heat your water? Quite clever! Do you ever use this design while driving? My only concern is that I want to be able to use the heating while driving if the engine isn't providing enough heat, and I don't like the idea of running propane anything while driving.

I'm curious about your suggestion of the pump at the cold leg. The heaters I'm looking at have a pump included, and I was thinking of cannibalizing the coolant pump from the rear heaters to run the in-floor system, but I was thinking of putting it on the hot end. Why do you suggest the cold end?
Hello,
No I don’t use the diy heater while driving. It’s really a system for someone who is seriously into diy and custom. What I like about hydronic is I’ve quickly added zones and had a greenhouse, a hot tub, a coil fan, a water cooled generator, etc all connected into the system.
Pump in the cool leg is not necessarily required just a customary location. I does help in very hot systems. The pump runs cooler. The quality and rating of the pump makes a difference. Some of the cheap plastic pumps I would want as cool as possible. I think there is another reason but I’m not remembering what.
We recently took out some espar and a and a clone. Was not working efficiently like my system does. They have some other advantages. Faster recovery being one. I can turn mine up if desired but then I waste fuel out the chimney. I’d rather turn the Wave on for 10 minutes while the floor heat warms up.
Doktari is offline   Reply With Quote
Old 08-15-2019, 05:07 PM   #9
Bus Crazy
 
CaptSquid's Avatar
 
Join Date: Nov 2015
Location: Billings, MT
Posts: 1,249
Year: 2003
Coachwork: Thomas
Chassis: HDX
Engine: Cat C7
Rated Cap: 84 passenger
Quote:
Originally Posted by inhof009 View Post
My bus is a full 35' and we will insulate well, but 5kW may not be enough if we encounter harsher weather, nearing 0F, which we intend to do eventually.
I've survived FOUR Montana winters in Brunhilde. 0į F is a nice day in a Montana winter. Two German Federbetten and two catalytic heaters keep me warm.
CaptSquid is offline   Reply With Quote
Old 08-15-2019, 05:49 PM   #10
Almost There
 
Join Date: Dec 2018
Location: Mt Vernon, WA
Posts: 96
Year: 1996
Coachwork: Bluebird
Chassis: G30 Bluebird Microbird
Engine: 1995 Chevrolet 350
Iíll second far infrared panels. Thatís the third heat source I use along with the Diy floor heat and Wave catalytic (formerly Olympian).
Itís all subjective thatís why I wrote ďit dependsĒ. Iím curious what insulation and heater you decided to go with.
Doktari is offline   Reply With Quote
Reply

Tags
5th item, diesel, heating, hydronic, interior

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 12:04 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.