Hot water heater or compact boiler

[Ken Kinsch]

Hi folks we have six small benches 3.3ft wide by 20ft long.My father used a 40 gallon hot water heater and piped each bench so we could do seed germination or rooted cuttings.The system has work well for over 20 years.I need to replace the tank and I want to switch the benches from 3/4 pipe to 1/2 PEX tubing so I can get more even heat across the bench.What would be more efficient a small boiler or a high efficient water tank?

[Eric Rohloff]

More efficient is all relative to efficiency of the unit your using. Are you going to need more output in the future? What's your budget?  Also why change the pipe? You can add more loops between what you already have unless the pipe is going bad.

[Ken Kinsch]

 The pipes are starting to go,there's to much space between pipes,so we converted one bench over to Pex tubing.I like the ease of working with Pex.My heating/ac guy says the hot water heater can not recover fast enough?

[Walter Gaipa]

Ken,

We used to use a propane hot water heater to heat three 6' wide x 24' long propagation benches. But while the unit was cheap to purchase it ran all the time. We replaced it several years ago with a Munchkin boiler. It is miniature, hangs on the wall and vents thru PVC pipe. It is extremely efficient and it easliy heats six benches. It is rated at 80k btu's.

Will not inexpensive, it is probably one of the best investments we made. The water runs thru tubes that sit on top of our rolling benches. It is a Truleaf system.

[Eric Rohloff]

This might get you saliva flowing.;)

Condensing boiler setup.

[Chris Sawyer]

I use a hot water heater slavaged from a wrecked RV and plumbed it to thermo syphon and heat my benches. It is kept on the lowest setting and keeps the flats around 70 on their bottoms in an unheated greenhouse here in Asheville, nc

[Ken Kinsch]

Thanks for the help,right after Christmas I will start working on up grading the benches to pex tubing.I stay with a hot water heater,just something more efficient.

[Walter Gaipa]

You might want to check out Truleaf as they make "roll and grow" tubing embedded into a mat to cover your benches. There system is also reverse return which insures even heating in every tube.