Sizing a radiant tube heater

[JohnCh]

I need some advice on sizing a radiant tube heater. After going through a lot of very useful threads here, I’m leaning towards the Reverberray LD-series, dual stage heater, but I’m conflicted over which size to get for my 28x45 shop with a 9'4" ceiling. The longest tube option for the 40k/28k burner is 20’, whereas the 50k/34k burner is available in a 30’ length. My conundrum is that I’m concerned that at even at the lower setting, the 50k may output too much direct heat for my taste (I prefer being cold to being hot), but that is countered by concern that a 20’ tube won’t provide enough coverage given that my workspace will occupy the full length of the shop. If they offered a 40k/28k with 30’ tube, I wouldn’t be posting this, but they don’t. The person at Reverberray said that I won’t notice the 6k difference between the lowest settings of the 2 units, and suggested I optimize for length with the 50k 30’ heater. What do you folks with tube heaters think is the best compromise?

As further background, I’m located about 30 miles Northeast of Seattle, so weather is not extreme. The average low/high temperature in the heart of winter is 33F/44F, but it’s not uncommon to get several days each winter where the overnight low is in the low-mid 20’s and the high is around 30F – of course I doubt I’ll be working in the shop on those days. I plan to keep the shop at ~40F when not in use, and heat it up to 60F-62F when in use. The ceiling and 2x6 walls are insulated with fiberglass batt insulation of unknown R-value. The tube will be located parallel to the long wall at a 45 degree angle.

Thanks,
John

 

[jonzer12]

With it at a 45 up in the corner you would probably be fine with the 50k unit. I have my 40k unit running down the center and I don't like to be standing under the hot end for too long, it will cook you. I planned my bench/ primary work area to be near the cold end, in shade from my mezzanine which alleviates the issue. With the longer units there is a huge difference in feel from the burner end to exhaust end. A lot of it depends on where you will be spending most your time.

Consult your vendor for the furnace. Once you get the slab warmed even the spots in the "shade" will be warm. I have the same 2x6 wall construction but I am only 36' long. My 40k unit is 22' long and rarely runs to keep it at temperature.

 

[JohnCh]

Thanks for the input. The vendor recommended the 50k 30' unit, but I didn't ask about temperature differences at either end of the tube. If that's fairly significant, then installing the furnace end on the side opposite of my work bench could be the right compromise.

Thanks,
John