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Anyone using instant water heaters for floor heat?

G

Greg Pack

Wash Weenie
I don't have floor heat, but must build a track heat system for my Coleman Automatics. It works on the same principle as floor heat. I would just circulate hot anti-freeze solution through plumbing attached to the rails of the autos to prevent ice build up. Coleman wants 4K for ONE track heat system that uses a 3 ph cartridge heater. I'm thinking one Rinnai would be plenty of capacity for two autos in my moderate temps. It looks like the Rinnais have really come down in price, too.

Any input is appreciated!
 
From what I know they are very efficient. Downside I've heard is life span is far shorter than conventional boiler. But if savings is considered and enough it could pencil out.

I just missed the instant hot water idea when I built new but would do it if I could have known then...
 
cfcw said:
I don't have floor heat, but must build a track heat system for my Coleman Automatics. It works on the same principle as floor heat. I would just circulate hot anti-freeze solution through plumbing attached to the rails of the autos to prevent ice build up. Coleman wants 4K for ONE track heat system that uses a 3 ph cartridge heater. I'm thinking one Rinnai would be plenty of capacity for two autos in my moderate temps. It looks like the Rinnais have really come down in price, too.

Any input is appreciated!
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cfcw,

I learned something reading an engineer's article in a Hydronic Trade Journal. The article showed that when the part of the heater or boiler that heats the antifreeze interacts to raise its temperature there is significant loss of efficiency vs just water. I try to use my Spirec Heat Exchangers as much as possible when heating my antifreeze. That way the fire within the boiler works with the more efficient fire-water but the heat still gets transferred to the antifreeze solution.

MJ
 
I know you asked about water heat for your tracks, but I'll throw this in anyway. Forum member Shorco1 has a Mark VII in pretty much an identical climate as yours. Mark VII advised an electric element that was readily available, cemented to the track. Last I heard from him he was pleased. You may try contacting him if you want to go that route. I seldom hear from him any more. It's like he owes me money and is avoiding me.
 
I used tankless to heat my floors for 18 years and its still working. For no more than you need, it should be an easy fix. What I had which was pretty trouble free was two heaters, but that was for a 6 bay. Used an open system, with a barrel of solution, and a pump. Used a temp gage for the outside temp and a temp gage in the return solution when it got cold turn it on, when the return temp got to 70 bypassed the heater, but kept circulating it.
 
cfcw said:
I don't have floor heat, but must build a track heat system for my Coleman Automatics. It works on the same principle as floor heat. I would just circulate hot anti-freeze solution through plumbing attached to the rails of the autos to prevent ice build up. Coleman wants 4K for ONE track heat system that uses a 3 ph cartridge heater. I'm thinking one Rinnai would be plenty of capacity for two autos in my moderate temps. It looks like the Rinnais have really come down in price, too.

Any input is appreciated!
Click to expand...

On the three wizards we used Rinnai heaters and they worked well, but what we had to do with the rails was to loop the pipe at the end and run the pipe down both sides of each rail to get enough heat, but it works well.
 
Are you thinking tankless for economy / efficiency. I think AO smith has a water heater that's more eeficient than tankless do not know if it would suit your needs.
 
Thanks for the replies so far.

I have limited space available for a traditional water heater, but I'm sure I could make it fit if it was indeed the best option. Coleman's system is essentially a wall mount tank with recirculating pump and three phase cartridge heater. In addition to the track heat Coleman recirculates the solution in pushlock hose throughout the gantry. That, and the blowdown are fairly effective in my mild climate. We only have 20-30 days per year that the antifreeze unit has to run, mainly at night to keep the units from freezing and the tracks from getting too cold. I don't have floor heat so if it gets too cold ( i.e "hard freeze")we just shut down anyway due to freezing on the apron. This is a rare event, but usually shut down about five days a year. No one washes then anyway because they know the cold snap will be over soon and will wait for it to warm up.

I like the idea of high efficiency, but since this system is in use only a handful of days a year I must be careful not to spend too much additional money up front for increased efficiency. The payback might exceed the useful life of the system.

Are there pressure/flow issues with the instant on systems? Do the typical recircualting pumps have enough head pressure to recirculate thorugh the gantry? I know at one place I used a procon to circulate. Probably not the best use of a procon setup but it worked pretty good.

Simple is good, so I may take a look at the heat tape setup.
 
cfcw said:
We only have 20-30 days per year that the antifreeze unit has to run, mainly at night to keep the units from freezing and the tracks from getting too cold.
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For such a short amount of time, would you consider an 10 gal electric unit? The upfront costs would be very low compaired to a gas unit. All you need to do is run an electical cuircut vs electric, gas line and venting.
I'm not sure I would want a tankless unit just sitting idle for 320 day a year. While they are reliable, they are complicated and expensive to repair. There really is nothing to a electric unit and parts are readily available.
I remember seeing an electric trough heat system in one of the parts catalogs but could not find it just now. I thought it was in Windtrax but cannot find it.
 
I think the 10gal electric water heater, would be a good idea in light of the few days needed, efficiency really wouldn't be an issue either.
 
If I were looking at heat tape i would consider Winterguard Wet as a first choice. they sell a ground fault hookup kit to go with it. It only comes on when the temp reaches a certain point. Look on their website for more info on how it works. it puts out more wattage than conventional heat tapes and needs no Tstat. I may be the odd man out here, but I have found tankless heaters to be limp and impotent - at least in the harsh climate where I am at.
 
One thing to remember about tankless heaters is that they are no more efficient than traditional boilers at converting gas to hot water. They only cost less to operate because they aren't using gas to maintain hot water when it's not needed. There are some that are more efficient (as much as 98% vs. about 80%) but they cost a lot more. It would probably never pay off in gas savings for such short-term use.

I would have to agree with a small electric heater and a recirculating pump. It would be cheap, simple and safe.
 
I installed the smallest tankless Rheem made for my two DS 5000 autos and also heat the 75 ft long trough on the roof. Works great!
 
What I do like-a lot- about the instantaneous units is no floor space is taken up. My floor space is essentially taken up in the equipment room so the water heater would have to be built on a mezzanine, or something big would have to be moved, or I put it in front of, or behind something else. I assume I could place the wall heater on the wall over my pump stand.

In regards to cost vs effectiveness, I don't mind spending a little extra to get what I want, I thought the reference Earl made was to the super efficient units that can cost thousands of dollars.

Googling Rinnais, it looks like they are a lot cheaper than they used to be. Amazon sells them for $850 with free shipping. I know installation costs must be considered for gas, but I've got that covered.

If I got a tank unit, I could intercept the power and install a relay to turn on power to the tank heater unit on a 45 degrees, then a second thermostat to turn on the recirculating pump at 35.

Will definitely look into the heat tape as an option. I know in the old days Coleman used it, then scrapped it and began recirculating through copper plumbing, but I don't know why.
 
cfcw said:
...If I got a tank unit, I could intercept the power and install a relay to turn on power to the tank heater unit on a 45 degrees, then a second thermostat to turn on the recirculating pump at 35...
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If it's a tankless heater, why would your power on and recirculate pump come on at different temps? Is there some type of warm up period that has to occur? Sorry, I'm unfamilair with using them, but am interested.
 
cfcw said:
In regards to cost vs effectiveness, I don't mind spending a little extra to get what I want, I thought the reference Earl made was to the super efficient units that can cost thousands of dollars.

Googling Rinnais, it looks like they are a lot cheaper than they used to be. Amazon sells them for $850 with free shipping. I know installation costs must be considered for gas, but I've got that covered.

.
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Here are prices $1600-$2000
http://www.pexsupply.com/AO-Smith-Vertex-Water-Heaters-10086000

See this video

http://www.popularmechanics.com/cars/jay-leno/4220014

I think the AO smith was 90+% efficient vs 80% for tankless. So based on your natural gas bill if there is a 10% savings and this fits the bill it may or may not be worthwhile.
 
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