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# Multi-room Baseboard Heat

## Multi-room Baseboard Heat

#1
03-10-03, 10:01 AM
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Multi-room Baseboard Heat

I am finishing my basement to add a family room, bedroom, bathroom and den. I plan to heat the FR, BR and den with electric baseboard heaters. The family room will have two 1500 Watt heaters, the bedroom and den will each have one 1500 watt heater. I would like each room to have it's own thermostat.

Can I do this on one 30 amp 240 volt circuit? I know the wattage would fit on that size circuit but how do I continue the circuit from one room to another keeping in mind that a separate thermostat controls each room?

And what is the difference between single and double post thermostats?

Thanks!!

#2
03-10-03, 10:14 AM
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Sorry. I meant what is the difference between single Pole and double pole thermostats.

#3
03-10-03, 10:24 AM
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I think I would use a minimum of at least 2 circuits, one for the LR with 12 wire and a double pole thermostat. Normally single pole is for 120v and a double for 240 where you want to break both legs. A little would depend on how the runs are and how the rooms are aranged. You need to use a big enough box a the room where you would put the therm to feed that one and the next room as there would be three wires (cables) coming in. Splitting this in 2 circuits would make the connections way more managable allowing for a smaller wire size instead of having to deal with heavy stiff 10 wire.

#4
03-10-03, 11:14 AM
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1500 watts x 4 bboards = 6000 watts/240 VAC = 25 amps total.
25 amps X 1.25 = 31 amps.

Can't use a 30 amp breaker for all four baseboards.

Use 2-20amp circuits as previously recommended. 2 baseboards per 20 amp circuit with #12/2 w/ground romex.

How are you going to mount the boxes for the thermostats?

#5
03-10-03, 11:36 AM
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This depends on the heaters. Have you already selected them? Can you tell us anything about them?

#6
03-10-03, 02:33 PM
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Thinman, Where does the 1.25 multiplier come in? To account for surge or what? Just curious.

I am hoping to mount the thermostats in boxes in the walls in the respective areas.

John, The only ones I've looked at so far are Dimplex Electromode. They are sold through Menards. But am open to suggestions if anyone has a recommendation.

www.dimplex.com

OK - Two 20a 240v circuits it is. One for Family room and the other for BR and den. I'm still not real sure how to connect the BR and den on the same circuit keeping them each on their own thermostat. Can I get a blow by blow on how this is generally done? Would it be similar to wiring 120 to a switched light and continuing to unswitched receptacles where three wire cable comes in to play? Or is that not necessary with 240 since there are two hots to begin with?

Thanks again!

#7
03-10-03, 06:53 PM
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Yes, it is similar to the light and unswitched recept that you describe. Run the wire to the closest room first then feed to the next room. At the first add a set of pigtails and splice to the wire feeding the second room with the incoming wire. Hook the tails to the therm of the first heater.

#8
03-11-03, 10:53 AM
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The first step is to install a sub-panel at a location "central" to all the new wiring-circuits. Run a 12/2 home-run from each thermostat to the sub-panel which eliminates complicated wiring and un-necesary splices. Cover the White wires of all 220 volt cables with Red marking tape. Use "deep 1900" boxes for the thermostat boxes. For the base-board heater connections, terminate each cable from the thermostat in a 1900 box with a rough-cover and with the 1900 box fastened to a stud. You must determine if you can make a connection at both ends of the heating-units and you must position the height of the boxes to conform to the location of the punch-outs on the back (wall) side of the units where the wires enter the connection box on the units.

You'll need a 20 amp circuit for the bathroom receptacle and you may need a wall-heater as well.If you go to the "Useful Electrical Sites" at the top of this column you'll find the WSA for the Honeywell "On-Line" catalog" which lists the types of thermosats available.-----Good Luck and give us a periodical "progress-report"

#9
03-12-03, 09:07 AM
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PATTBAA,

Thanks for the suggestion. The current panel, which still has plenty of breaker capacity, is located in the basement about 30 feet from the area I am finishing so it might be overkill to put a subpanel that close but I can definitely see advantages to doing this (like not having to power down the whole house to add new circuits and not having to pull all of the cable through as many joists). Especially since I am also considering running wire for a future outside hot tub and pond equipment. I will have to cost it out to see if it fits the budget.

The bath is situated such that a wall heater could only go right next to the shower. Which I understand to be a no-no. I have already purchased a combo fan-light-heater for that area.

#10
03-12-03, 09:46 AM
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DIY_Dave

The 1.25 multiplier is for continuous duty.

Here's how I recommend you do the installation:

Buy nail-on non-mettallic deep boxes for the thermostats. These will provide ample space to make splices and mount the thermostat.

Route the home run cable from the panel to the first thermostat box. Route a cable from the first thermostat box to the BB heater.

Route a cable from the first thermostat box to the second thermostat box. Route a cable from the second thermostat box to the BB heater.

Hardwire the cable at the heater: at the BB heater, punch a hole in the wall large enough for a romex cable connector. Be sure to line up the hole with the knockout in the BB heater. Install the cable connector onto the romex cable. Connect the cable conncter to the BB heater. This eliminates the need for a junction box in the wall behind the BB heater. The BB heater provides ample space for splicing the wires.

If you use a j box behind the heater, you would have to punch a large enough hole in the BB heater so the j box splices are readily accessible. This is a waste of time.

Repeat the above steps for the other two BB heaters.

Hope this helps.

#11
03-12-03, 10:52 AM
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I would wire the heater's according to thinman's instructions. Deep plastic nail-on boxes (22 cubic inch) will provide plenty of room for 3 12-2 cables in the first box and 2 12-2's in the second.

The difference between a single pole and double pole thermostat is that the single pole only breaks power to one leg. Just splice the other leg (phase) together in the back of the box. Don't think there's any reason to have to go with a double pole. You can also buy thermostats that mount on the baseboard heater wiring compartment (take the place of the blank wiring compartment cover) if you don't really need the convenience of the wall mounted thermostat. Would obviously require less wiring.

#12
03-14-03, 08:16 AM
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Because this is a DIY project and the panel is only 30 ft. away I suggest that DIY-Dave install a 12/2 Home-rune from EACH thermosat DIRECTLY to the panel.The fewer wires in an outlet-box the better,the fewer the splices the better, and the less current on a circuit the better. Complicated wiring for a DIYer is not practical just to save 30 ft. of cable and 1 circuit-breaker. I believe an outlet-box at each heater connection is better than "floating" cables. It's not necessary to have any splices in outlet-boxes "readily accesssible." You don't have to have the splices for a baseboard heater any more "acccessible" thru the heater than you have to have splices for liting fixtures "accessible" thru the fixture. I advise "deep" 1900 metallic outlet boxes with a metal "rough-cover" for the thermosats. The tap on a metal cover is much better than the tap on a plastic outlet-box. "Strip" the threads of the tap on a plastic box and you've got a problem.-----Good Luck!!!

#13
03-14-03, 08:34 AM
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Pattbaa, not sure why you recommend the device box at the heater location. Your proposed wiring method will require only one cable to each heater location. Why do you want to make a splice in a box that will be covered by the heater (which would require removal of the heater to access if the DIYer's splice failed) when all you have to do is run your cable directly through the 1/2" knockout in the back of the heater into the heater wiring compartment?

Regarding running a separate homerun for each of the 4 heaters instead of 2 homeruns for the 4 heaters, Dave says he has plenty of spare circuit capacity in his panel but you are talking about 8 spaces required instead of 4. I guess if push came to shove, he could "splice" and pigtail in the panel if he needed that space back down the road. Panels are not supposed to be used as junction boxes, but sometimes you gotta do what you gotta do.

#14
03-14-03, 01:21 PM
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DIY-Dave mentions heating three rooms which = 3 thermosats and 3 home-runs.----It's difficult fastening a baseboard unit to the wall when you have to shove "floating" cables with slack into the wall and if there's two 12/2 cables to be connected- 2 Blacks, 2 Whites, 2 Ground-conductors- it's not practicle to connect six #12 wires in the small connection-box on the heater.

#15
03-19-03, 02:28 PM
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Originally posted by PATTBAA
DIY-Dave mentions heating three rooms which = 3 thermosats and 3 home-runs.----It's difficult fastening a baseboard unit to the wall when you have to shove "floating" cables with slack into the wall and if there's two 12/2 cables to be connected- 2 Blacks, 2 Whites, 2 Ground-conductors- it's not practicle to connect six #12 wires in the small connection-box on the heater.
Too each his own.

One cable is routed to each baseboard heater. If the sheetrock is not up yet, the cable should be stapled accordingly. This includes within 12" of the baseboard. This would not be considered a floating cable IMO. If the sheetrock is up, it's perfectly legal by the NEC to have a floating cable inside the wall.

3000 watts/240 volts = 13 amps (actually 12.5) per 20 amp circuit.
In reality only 2 - 20 amp circuits are required based upon DIY_Dave's plan to use 1500 watt baseboards. It would be nice to know the actual square footage of each room to see if 1500 watts of heat is sufficient.

I've installed dozens of baseboard heaters in the manner I described and have not been red-tagged by the inspector.

With all due respect PATTBAA, your method incurs more cost and more work.

This applies to the your opinion about splices not being required to be readily accessible. I wouldn't want to remove a baseboard heater so I can get to the splice. If the box is not going to contain splices, why waste the time and money to install it?

#16
03-20-03, 07:20 AM
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Thanks to all for your input.

Thinman , The areas of the rooms are: Den - 120 sq. ft., Bedroom 160 sq. ft. and Family room - 410 sq. ft.

I will be running a forced air duct and return to each room, mainly for ventilation but doubt that would be enough heat to keep it comfortable during cold Wisconsin winters so will be relying on the baseboard heaters to keep it toasty.

#17
03-20-03, 09:24 AM
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Art. 410.14 applies to surface-mounted flourescent-fixtures. I plead Guilty ( Ignorance of the Law is no excuse!!!) to violating this Article many times, for example, when installing a surface "2 X 4" that has to be positioned with the end of the fixture covering a flush ceiling outlet-box. The top/back of the fixture completely covers the box.It's helpful that this Art. was referred to although it doesn't apply to heaters. Many of us will have to "re-think" when installing surface-flourescents. An electrical inspector would have to dis-assemble a fixture to detect a violation and I'll guess many inspectors either don't enforce or don't know about this requirement.

#18
03-20-03, 01:09 PM
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Originally posted by DIY_Dave
Thanks to all for your input.

Thinman , The areas of the rooms are: Den - 120 sq. ft., Bedroom 160 sq. ft. and Family room - 410 sq. ft.

I will be running a forced air duct and return to each room, mainly for ventilation but doubt that would be enough heat to keep it comfortable during cold Wisconsin winters so will be relying on the baseboard heaters to keep it toasty.

The following calculations are based strictly on heating the rooms with baseboard heat. The rule of thumb formual I use is 2 watts X the rooms cubic ft. measurement.

Den: 120 sq ft X 8 ft (ceiling) = 960 cu. ft X 2 watts = 1920 watts which would be a 2000 watt baseboard heater.

Bedroom: 160 sq ft X 8 ft = 1280 cu. ft. X 2 watts = 2560 watts. A 2500 watt baseboard heater would work.

Family Room: 410 sq. ft. X 8 ft. = 3280 cu. ft. X 2 watts = 6560 watts (lots a watts here). If I'm not mistaken, 2500 watts is the largest sized bboard heater available.

But since you mentioned that the baseboard heaters will supplement the forced air heat. You should be OK with the sizes you want to install.

You realize that baseboard heaters use the watts don't you (they also take up wall/floor space too)? How much do you pay for a kilowatt of electricity in Wisconsin?