Recommendations for replacing a baseboard radiator with toe-kick radiator

jsantoku · March 22

Hi HeatingHelp community, I'm planning to replace a baseboard radiator in my kitchen with a toe-kick radiator (so I can install some cabinets).

I've got some questions regarding the plumbing and electrical involved in this.

For a little background:

My house's hydronic heating system includes
- 6 baseboard radiators on the main floor (I need to keep the rest as is but just replace the kitchen radiator)
- 2 small baseboard radiators on the 2nd floor.
- Lochinvar fire tube boiler`
Half of the kitchen spans a crawlspace and the other half spans the basement, which has a finished ceiling, so only part of the plumbing is exposed (what's below one end of the radiator). This was all done before we bought the house a couple years ago…
I believe the system is all on a single loop, since I see only two pipes into the ceiling above the boiler. I think the primary bedroom radiator right above the boiler and crawlspace behind the boiler is first in the loop.
I believe the system has 1 primary loop and 1 secondary loop. Please correct me if I'm wrong, given the included photo.

Plumbing questions:

Do I need to install an additional secondary loop just for the toe kick radiator? If so, I'll have a few more questions…
If no, then what's the proper way to to connect it?
- Based on my research, I could use 2 monoflow tees to connect to the 1/2" PEX of the main loop. The 1/2” PEX to/from from the toe kick would be a bypass off the main loop (to avoid pressure loss on the downstream radiators in the loop). I've include a quick sketch of this.
Is PEX-B with copper crimp rings fine for this install (I have these tools)? Or should I use copper pipe with crimp fittings or sweat fittings?

Electrical questions:

I understand the toe-kick radiator should be attached to a 120V circuit, right?
Do I need to also wire the toe-kick radiator to the boiler control system, so that it kicks on with the thermostat? If so, I'll have some questions around parts for this, and how exactly to connect?
I understand there might be a low-temperature aquastat option to avoid wiring to the boiler controls, is this correct?

Radiator recommendations?

This is the one I've been seeing most commonly: Beacon Morris K84 Twin-Flo III Kick Space Heater. The kitchen I need to heat is about 160 sq ft.

With your responses, keep in mind that I'm a homeowner who has done some minor plumbing and some 120/240V electrical work at home, but I don't have a ton of experience…

Thank you for any answers or recommendations!

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Screenshot 2026-03-22 at 15.33.25.png

HydronicMike · March 22

I honestly recommend you try to consider something else. I ran a toe kick in my one bathroom, hated it so much I disconnected it. Because we super insulate that bathroom on a remodel, turns out we didn’t need heat at all.
Without knowing your btu needs, or the layout, Are you sure you even need heat to replace the radiator?
Is there an option for panel radiators? I had a customer do two tall, narrow, flat panel radiators on each side of a dining room slider in an open kitchen and it provides plenty of of heat. You could even do all toe kicks with flat, radiant baseboard.

EdTheHeaterMan · March 22

So to start with your 3/4" baseboard loop can have up to 67 feet of 3/4" baseboard (average number) based on the 600 BTU per SqFt of baseboard heating element. this is of course a maximum and it appears that you don't come anywhere close to that. The next thing is that the Beacon Morris is a 1/2" pipe connection. With that being placed in series with the 3/4" baseboard then the smaller diameter pipe needs to be the governing factor in how much heat that loop can carry. So piping the kickspace heater is not as simple as you might thing,

EdTheHeaterMan · March 22

https://forum.heatinghelp.com/discussion/comment/1892599#Comment_1892599

Your situation is completely different. You are removing heat emitters and replacing them with a different type of heat emitter in a large room. You are not working on a small bathroom with other rooms adjacent to it. let me look a little closer at your total situation and see what is best for you.

EdTheHeaterMan · March 22

Everything you have said sounds exactly correct. There is one change I would make to the crawlspace/basement piping where you remove the baseboards and replace them with the kickspace heater. I would add a ball valve on the run in order to throttle the proper amount of water diverted to the kickspace heater. It will also allow you to purge that loop by closing the run completely to force air out of the under-cabinet coil. Then you can return the ball valve to a partially open position that delivers the proper amount of heat.

Getting the proper balance for the under-counter heater with the ball valve is going to be a matter of trial and error. Some will recommend a diverter tee fitting or MonoFlo® tee. I would stay away from that and use the ball valve instead, because it gives you the control you need to adjust the flow to the heating element.

The smallest under-counter heater is all you need. Since you are only removing about 7 feet of baseboard element, the K42 Twin-Flo III kickspace heater is roughly equal to the output of the emitter you are removing. Unless the kitchen is too cold with that existing baseboard, you should not use the K84 Twin-Flo III kickspace heater. that may makew the room overheat or steal heat from other areas of the home.

Since you are using only one loop of 3/4" PEX tubing, there is a chance that your piping system can only handle about 36,000 to 38,000 BTU/h. If your home needs more than that on a design day, you may find that by using the larger heater, the system becomes out of balance and your rooms will not reach the thermostat set temperature.

This would only occur on the few days when you experience design conditions (the coldest days of the year), but if that happens, you may want to redesign the system with a larger 1" primary loop and branch off into two separate 3/4" PEX loops.

Recommendations for replacing a baseboard radiator with toe-kick radiator

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