chamook
New member
- Location
- Orofino, Idaho, USA
This is my first post after skulking around this site for over a year. Apologies if this is not the appropriate forum but none of them seem to exactly fit my question so I'm going with NEC.
I've got a fan forced electric unit heater, 240V, single phase, 7.5 KW. This is a very nice unit (Modine HER 75B 1101) and quality appears to be several notches above most of the run of the mill heaters I've seen. I have an opportunity to buy another of these at an excellent price but I really don't need another 7.5 KW worth of heat in my workshop or garage.
I've noticed that most of the consumer grade heaters are field configurable to reduce their wattage/btu output, and this is done by rearranging some jumpers. I'm assuming that all this does is bypass one or more of the heating elements - does that sound right?
In looking at both the wiring schematic and the physical arrangement inside my heater, I see three elements, all connnected in parallel by copper straps that bolt to the elements. My question is, if I wanted to reduce the output of this heater to say 5 Kw, could I just disconnect one of the elements? They are coil type elements, arranged one in front of the other in front of the fan. I figure I'd disconnect the first element in front of the fan so the heat is not blowing over the inactive element. Here's a link to the schematic at the Modine site. http://www1.modine.com/publications/litnav.php?c1=CHVAC&R&c2=Modine&c3=02+-+Electric+Unit+Heaters
Now you might wonder why in the heck I'd do this instead of just buying a 5 KW heater? Fair question, and the answer is I can get this much higher quality heater for not much more than a consumer grade 5 kw. I'd also wire it as if it were a full 7.5 kw heater so I or somebody else could safely connect the inactive element if more heat was needed. I have called Modine but predictably I'm getting a standard line of " we don't recommend field modification of our heater, voids warranty etc.) I do notice though in their troubleshooting guide that if the problem is insufficient heat, they recommend testing the elements to make sure one is not burned out. So, from that I'm thinking if the heater can run safely without an element (burned out), it can run with one disconnected. Do I have any logic going here?
Thanks for any advice you can offer!
I've got a fan forced electric unit heater, 240V, single phase, 7.5 KW. This is a very nice unit (Modine HER 75B 1101) and quality appears to be several notches above most of the run of the mill heaters I've seen. I have an opportunity to buy another of these at an excellent price but I really don't need another 7.5 KW worth of heat in my workshop or garage.
I've noticed that most of the consumer grade heaters are field configurable to reduce their wattage/btu output, and this is done by rearranging some jumpers. I'm assuming that all this does is bypass one or more of the heating elements - does that sound right?
In looking at both the wiring schematic and the physical arrangement inside my heater, I see three elements, all connnected in parallel by copper straps that bolt to the elements. My question is, if I wanted to reduce the output of this heater to say 5 Kw, could I just disconnect one of the elements? They are coil type elements, arranged one in front of the other in front of the fan. I figure I'd disconnect the first element in front of the fan so the heat is not blowing over the inactive element. Here's a link to the schematic at the Modine site. http://www1.modine.com/publications/litnav.php?c1=CHVAC&R&c2=Modine&c3=02+-+Electric+Unit+Heaters
Now you might wonder why in the heck I'd do this instead of just buying a 5 KW heater? Fair question, and the answer is I can get this much higher quality heater for not much more than a consumer grade 5 kw. I'd also wire it as if it were a full 7.5 kw heater so I or somebody else could safely connect the inactive element if more heat was needed. I have called Modine but predictably I'm getting a standard line of " we don't recommend field modification of our heater, voids warranty etc.) I do notice though in their troubleshooting guide that if the problem is insufficient heat, they recommend testing the elements to make sure one is not burned out. So, from that I'm thinking if the heater can run safely without an element (burned out), it can run with one disconnected. Do I have any logic going here?
Thanks for any advice you can offer!
