Forced hot water heat options in small pantry?
I'm in the middle of a remodel and the rough plumbing will be starting soon. We'll have a small pantry/laundry room with basically no space for a hot water baseboard. The room is 5' deep and 8'3" wide. Their is a 30" pocket door roughly in the middle of one of the 8'3" sides. After entering the room, the 5' wall to the left is entirely base cabinets with wall cabinets above (i.e. the pantry). The 5' wall to the right is an exterior wall with one 2'Wx4'H window, and a side-by-side front load washer and dryer. The dryer will be vented directly to the exterior. The exterior wall is 2x4 and will be sprayed with closed cell foam. Below this room is a finished basement which likely won't go lower than 55 degrees F, and above is the 2nd floor. The ceiling is 7'6" high.
This would be part of a the 1st floor heating zone which is 1244 square feet.
The contractor has presented 2 options so far:
1.) The smallest kickspace heater he can find under the cabinets on the left wall. He says this will be way overkill for such a small room and may make it too warm. He says that could be mitigated by leaving the fan off, but after doing more research I'm concerned that the base cabinets will get too hot, making it unsuitable for pantry storage which should be cooler and dry.
2.) Electric radiant floor heat. It's such a small room with not a lot of surface area exposed to the exterior AND will have a dryer (although not running all the time).
Obviously, no one will be spending any significant amount of time in this room, other than maybe to fold laundry on the countertop above the washer/dryer. On the other hand, we may prefer to have the door closed most of the time. Regardless, maybe we can get away with no heat at all in this room, or maybe we could use electric radiant floor heat as a backup/insurance in case I'm wrong?
Another thought I have is to have some kind of diverter to bypass some of the hot water flow around the kickspace heater. Can this be done in such a way as to dial down the max BTU output of the kickspace heater to an appropriate level for this room? I don't know yet if this will be near the beginning/middle/end of the zone loop, and there might not be a choice given other constraints.
I did a back-of-the-envelope heat loss calculation through the exterior wall, but I'm not sure it's right:
For the wall:
7.5 x 5=37.5 square feet (minus 8 square feet for the window)
Insulation is R-19
70F delta-T (worst case)
29.5 x 1/19 x 70 = 108 BTU
For the window (U-value 0.25 and 8 square feet of glass):
8*.25 x70 = 140 BTU
For the tile floor above 55F basement with R-19 fiberglass insulation between joists:
8.25 x 5 = 41.25 square feet
41.25 x 1/19 x 15 = 33 BTU
Total heat loss through the exterior wall and floor is 281 BTU, which seems really low, and only a fraction of what is put out by a kickspace heater. If correct, I'm guessing that heat loss due to air leakage around/through the floor, window, and dryer vent penetration will dwarf this, but I'm not sure how to guestimate that. The hole for the dryer vent will likely be cut much later after the insulation is sprayed.
Comments
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Electric radiant floor heat would not go under the cabinets, so would only cover ~30 square feet.
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Panel radiator with a TRV?
https://www.supplyhouse.com/Buderus-3-21216-Model-22-12-x-16-Hydronic-Panel-Radiator
The TRV can be set to maintain a lower temperature that the rest of the home with the pantry door closed. This way the room won't over heat even with the smallest radiator being too large for that small space
Be sure to allow for enough air for the laundry exhaust from the clothes dryer
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Had a somewhat similar situation in Vermont a few years back — only it was a bathroom. Electric radiant floor heat was by far the easiest and simplest way to go. And it's easy to control…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Panel radiator in a floor grate or hung in the ceiling?
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How many outside walls?
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Since you said, it's not going to be occupied much, a small electric blower fan might be your best bet $$$$ wise. Get a quote. Mad Dog
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Just 1 outside wall (one of the short sides). See my back-of-the-envelope heat loss calculation.
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Small electric heater or T-Stat controlling toe kick fan, let the HW flow
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If toe kick fan is controlled by a thermostat, it will still have 180F water going through the fins with the fan off. Will that overheat my pantry cabinets with convection or radiant heat?
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Will the cabinet get warm, possibly. Too the point of excessive NO.
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Does it even need heat. Door closed often? One outside wall 5' wide?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
It doesn't need any heat. No one is living in it or taking a shower in it. Waste of money to heat it. Leave the door open most of the time especially in cold weather.
You could use an electric cabinet heater. They are small and fit in one stud bay and have self contained thermostats and can run on 120 volt. They are semi recessed usually with about 1- 1 1/2 sticking out of the wall. The cost of doing anything with HW is more than its worth
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Yeah my wife said the same thing (i.e. doesn't need heat). She thinks the dryer will make the room warm but I'm not so sure. Regardless, the room is the size of a walk in closet. We were planning on keeping the pocket door closed though in case the laundry area is cluttered. Maybe we should get a door with louvers? That would also allow makeup air from the rest of the house when the dryer is venting.
We could have electric radiant floor or wall heater just in case.
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If there is plumbing in there i'd heat it just to make sure that doesn't freeze.
do the kickspace heater with the fan controlled on a thermostat, put a piece of foam insulation above it in the bottom of the toekick to keep the heat out of the cabinet. a small panel radiator or runtal radiator are also options. plumb it with a bypass if it is a series loop.
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What is the point of a bypass? Is that to reduce the GPM through the heater? Could the GPM be made adjustable between the heater and the bypass? Could THAT be temperature controlled instead of the kickspace fan?
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Normally the bypass would be 2 valves, one that controls the flow through the coil, the other that controls the flow through the loop.
you could use a mechanical fixed thermostatic valve that would mix it down to a specific temp, you could use a thermostatic radiator valve, you could do it electronically, you could do it with a 3 way zone valve. the mechanical option is somewhat expensive, the electronic option is very expensive.
if i were worried about heating food in long term storage i would find a place to put a panel radiator that isn't near the food.
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you have maybe an 800 btu load, if it received no other heat, which it does
Put a 150W incandescent light 💡 in there
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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or a loop of large metal pipe.
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that’s 100% Efficient 😇
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Second vote for toekick heater with its own thermostat on the fan. It will produce negligible heat when the fan isn't running.
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Regarding hydronic toe kick with a thermostat controlled fan, are there any specific product suggestions?
I assumed that my GC would just use a K42, but doesn't that turn the fan on and off based on the water temp? Is the idea to wire up a thermostat and relay to this so that line voltage to the fan is cut when the pantry thermostat rises above the set point? In other words, for the fan to run, the whole 1st floor zone needs to be running to circulate hot water AND the pantry thermostat needs to be below its set point. If so, with such a high BTU output, wouldn't the fan be constantly short cycling?
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A 2' section of 2 tube runtal tucked in next to the washer or dryer would be 3x what you need
https://www.supplyhouse.com/Runtal-UF-2-24-2-ft-UF-2-Baseboard-Radiator
short cycling of a fan doesn't really hurt anything but it could be annoying. you could slow it down with a speed control if it is the right type of motor.
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That unit has a thermostatic switch on the incoming water pipe. I'd put a room thermostat in series with the switch, so that the fan would only run when the water is hot and the room needs heating. It would be possible for the room to need heat and not be getting it, if the rest of the zone didn't need heat. But hey, it's not an occupied room.
Simplest would be just to use a $15 line voltage thermostat for the room thermostat.
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So you literally just wire it to a wall box instead of direct hardwire and use any line voltage thermostat. I looked in the manual and it actually suggests this as an option (i.e. not some kind of unofficial hack). Just have to convince the GC to have the electrician do this.
Another problem is that he doesn't want to cut access panels in the cabinet bottoms for the kickspace heaters. He says he's never had one fail and I can just cut a hole later if I need to. Seems to me like it would be much harder to cut after the cabinet is installed.
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Is there access from underneath?
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Finished basement with drywall ceiling. Other kickspace heaters in the kitchen are over unfinished basement or garage with drywall ceiling. The K42 manual says in bold to cut an access panel in the cabinet floor for annual cleaning and maintenance. It also says to install at the finished floor level. The pantry will have a tile floor and cabinets go in before tile (after for wood floor). I'd have to insist that cabinets are shimmed up by whatever thickness the tile will be when installed. I'm worried that the GC will push back on this given that he has pushed back on cutting access panels.
My previous kitchen had a tile floor and kickspace heater with no access panel. Kickspace heater was directly on subfloor (i.e. below tile). The bleeder valve leaked, so I had to chip away grout to remove front cover. Luckily, I could reach the bleeder valve from there, and would have had to cut through the cabinet floor otherwise.
Isn't accessibility required by code since there is a line voltage connection?
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The bottom line is You write the check.
Asking for the cabinets 3/4 of an inch because of a tile floor is standard and shouldn’t have to be asked for anyway.0 -
281 BTU? Turn the light on
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Not with an LED light.
a 100W incandescent would probably be very close though.
Worse case, why not loop some pex around the floor, or, in the outside wall surface? If it needs so little, any little amount you add is going to be fine, no?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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If you use a toekick you must have an access panel. If you have sheetrock below how would you install it without an access panel?
For the amount of heat you need its not worth the stress you don't need any heat
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I still have toekicks in the kitchen that will have the same problem regarding access, so it needs to be addressed regardless.
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I realize that having a removable front grate probably satisfies the electrical code requirement for access. I don't know if there is a similar requirement in the code for access to mechanical components (i.e. the fan). GC says they will be installed with some amount of play so that they can be slid out at least partially. I don't totally follow how that would work, even with PEX.
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Isn't ceiling radiant also a thing?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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the cabinets should be on top of the tile for many, many reasons. you need an access cut in the cabinet if you install a kickspace heater. code requires you follow the manufacturer's instructions.
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This is the 2nd GC I have ever worked with (the 1st was for bathrooms) and both were adamant that wood flooring goes in before cabinets while tile goes in after. My suspicion is that this is about efficiency because they don't want the tiling sub to have to come twice: once before all the cabinets go in, and again AFTER in order to do backsplashes, tubs, showers, etc. The only exception would be tile under a free-standing vanity in a bathroom.
That being I'm said, I'm fine with this as long as the cabinets are shimmed to the level of the finished tile floor height. However, the finished floor height depends on the thickness of the selected tile, which can vary. I suppose that the cabinets could be shimmed up to the worst-case final floor height (i.e. thickest possible tile), and if that turns out to be a smidge higher than the actual final floor height, the gap could be covered by the toe-kick panel (assuming it's a bit oversized) or shoe moulding.
Unfortunately, I didn't have this all spelled out before signing the contract.
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Here are some pros and cons regarding tiling before vs after:
https://www.tileletter.com/should-cabinets-be-installed-before-or-after-tile/
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If you like this idea, and you really want to get fancy, Honeywell makes something called a Winter Watchmen that you plug a lamp with that 150W bulb into. That will shut the bulb off when the room temperature goes above a given setting, like 55° or 60°
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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I have seen the tile go in both ways usually after and always after when remodeling and keeping the cabinets.
One thing to watch out for is an existing dishwasher. If you add tile you may not get the DW out.
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This is a total gut.
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