Thoughts on Runtal Electric Radiant Panels
Hello all,
I’ve learned so much here but I haven’t seen this discussed before. A quick search finds some talk about Runtal’s hydronic baseboards. But I have a client who is very interested in Runtal’s electric radiant panels. I’ve never seen one in person and can’t find much info, good or bad, about them.
The house is in Sebastopol, CA. 1967 vintage with 2×4 walls and lousy fg batts installed then. We’ve remodeled the kitchen and bathrooms and we’ve air-sealed the ceilings and blew deep cellulose in the attic space, air-sealed the rim joists and floor penetrations and replaced the old aluminum windows, but we aren’t addressing the exterior walls at this point. There will be a 9.6 kw solar array providing more than enough power for a conscientious retired couple. They would like to use the electric radiant panels.
What do you think?
Much thanks in advance,
Ron
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Replies
They are like any other resistence heat source except that they are more massive, so they retain heat and therefore smooth out fluctuations in temperature. Add line voltage thermastats that sample temperature differentials and you get very nice temperature control and room-to-room zoning. I like them, but they are expensive.
They are also less efficient than heat pumps. The COP of electric resistance heat is 1, meaning that they put 1 kW of heat in the house for every kW of electricity consumed. Heat pumps can do better, with COp of 3+, meaning 3 kW of heat into the house for each kW consumed. Plus, heat pumps can do heating and cooling. Sebastopol has a nice climate, but cooling is still great to have. If the house already has central A/C, upgrading that to a heat pump might save money and energy.
Of course I agree that a heat pump would be preferable. But the bids are coming in at $27,000 and up for a Mitsubishi. That's significantly more than the electric Runtal panels.
If you couldn't install the preferred heat pump system, what would you use?
That's a tough one. With the installed cost of heating equipment running 3x-5x the cost of the equipment itself, it makes it hard to do the right thing. Why is it that the HVAC industry, which has so few competent practitioners, also has such abusive pricing? Market forces are truly not working here. I guess the answer to your question is to use the Runtals. With a mild climate, the cost of resistance heating is relatively low and your payback for the heat pumps will be forever.
>" But the bids are coming in at $27,000 and up for a Mitsubishi."
$27K worth of Mitsibushi is simply ridiculous, unless this is a 10,000 square foot uninsulated ranch or something.
The only way to bid it up that high for a normal sized house is to go with the "ductless head in every room" approach, which ends up with LUDIRCROUS oversizing, so obscenely oversized that it cuts in to both comfort and efficiency.
On retrofit projects in my area (99% design temps in low single-digits F, 1% design temps in the mid-80s) a typical 2000 square foot 2x4 framed house with clear storms over single panes takes no more than 3 tons of compressor at <$15K of Mitsubishi or Fujitsu equipment when competitively bid. In recent memory I've even seen a ~3000' house (half of which was leak 70s' vintage 2x4 construction, the rest a 2x6 framed addition) install 4 tons of Fujitsu (6 zones total) for a bit under $15K (less than $12K out of pocket after state & utility subsidies.) That house was in a coastal MA location with a 99% design temp of +13F, and 4 tons is definitely oversized for their actual loads (they had to upsize to get the extra zones.)
If the loads are so egregious that it actually needs $27K of Mitsubishi to stay comfortable due to the crummy leaky FG and lousy windows, spending half the $27K on retrofit air sealing & insulation, window upgrades (low-E storms over any reasonably tight single panes) would likely reduce the loads to where the equipment size would be cut by half or more. The 99% & 1% design temps for nearby Santa Rosa are 32F & 91F respectively, with a NEGATIVE latent cooling load @ 50% RH.
This climate would need only fairly modest amounts of equipment , even with a leaky poorly insulated 2x4 framing. But dense packing cellulose over existing ratty R11 batts is actually pretty easy, and would tighten up the place by quite a bit, and would be far cheaper than an "extra" couple tons of ductless, and would provide more comfort than upsized equipment.
This isn't a "Runtal = BAD, heat pump = GOOD" comment. Like any other heating project a room by room Manual-J load calculation (isn't that already required by Title 11 anyway) would be a starting point for finding the "right" solution. It takes surprisingly little resistive heating panel to cover the load with a design temp of +32F. but the goal should be comfort & efficiency, independent of the equipment type. Oversized Runtal rads are just as ridiculous as oversized heat pumps from a comfort point of view.
"Oversized Runtal rads are just as ridiculous as oversized heat pumps from a comfort point of view."
No. TRIAC switched line voltage thermostats will turn the unit on or off every 20 seconds or so, offering essentially infinite modulation. The smallest Runtal is 1500 BTUh.
If I were generating my own electricity, I personally would go with the Runtals. Your clients have expressed interest and they will be pleased with their comfort and ease of zoning. Do they prefer their bedroom to be cooler at night and warmer when they wake up? No problem. Your climate is mild so depending on your load calculations you could consider thermastated towel warmers to heat bathrooms.
Hi Peter and Fred,
Thank you both very much for your help. I was leaning in this direction and needed a little reassurance that the Runtals were an acceptable solution.
Thanks again!
In a place that doesn't need AC (or need very little of it), your best bang for your dollar is installing a single wall mount mini split in the living space and resistance heat elsewhere.
During the day when the doors are open, the wall mount can supply most of the heat for the house with the panel rads taking over when the doors are closed at night. This would give you most of the benefit of a full heat pump setup at much lower cost.
You should be able to get a high quality wall mount installed for under $5k.
Ron,
I would definitely support the idea of going with a heat pump over resistance heat panels if at all possible. However, like you, I faced absurdly high quotes for their installation. My electrician suggested cove heaters and I have found them to be a good fit for us, even in a much harsher climate.
I do pay far more for electricity without question, but I do not anticipate any maintenance needs. We don't need seasonal air conditioning if we handle our ventilation carefully like your client. That said, I was incredulous at the price of the Runtal units. I paid a bit over 5,000 for all the heater units, installation, wiring and panel work in our 2800sf house. As your client will need panels in most every room, I suspect they are facing a considerably greater cost.
I would also point out that resistance panels like Runtal's will heat both faces equally, so half of your energy output is going to warm the wall. The small air gap behind the heater unit will not significantly change that. You mentioned the client's existing wall insulation is very poor, so the loss of useful heat per unit will be notable. The units will also impinge on furniture placement more than might be expected.
At risk of sounding like an evangelist for cove heaters, I would point out that their high location is advantageous and the heat distribution is remarkably even. We don't arrange our furniture or our lives around the heater locations.
Admittedly, my walls are about R36, so I do have the advantage. Still, for the poorer wall insulation, I think it more useful to use the cove heaters, which I perceive as projecting the majority of radiant energy forward. Yes, the whole unit heats up and warm air does pool above them. I just figure this adds to general heating of the air. The emitting face is about 3-4" off the wall and the does not warm as one would expect. Perhaps the special paint on the front face is the trick.
Comfort Cove is the brand my electrician provided. Their are others, but I can only describe these for performance. They are not paintable, so be sure to note that. Some colors choices are available, but for us, white was the logical choice. After a few weeks of living with them, they become like wallpaper and disappear from perception. The wall units for heat pumps are a bit more obvious and they do make noise. I would note my wife drove the final decision, but that seems to not be woke now.
The Runtal's are very stylish, but I would only look to them for the bath.
Hi guys,
Thank you all for your thoughtful insights. The clients are still wrestling with this decision. I've solicited three bids now for heat pump systems. All the quotes are very similar. It is what it is. $27K for a heat pump (which doesn't even include pulling wire and a new circuit) vs. $11K for Runtals (plus a day of pulling wires through the crawlspace) = about $15,000 to offset installing many additional solar panels. I think this is the direction I'm going to recommend.
Thanks again. All of your smart comments helped organize my thoughts about this one.
I'd suggest getting a quote on Akos's idea too: one minisplits and lots of radiant panels. Also, $11k sounds high for the radiant panels, so you might price out some others such as the radiant cove heaters mentioned.