Thermostat for Hydronic Kickspace Heater

Sparkie212

I installed a Beacon Morris K42 Kickspace heater and it is working as expected. I would like to have it controlled by a thermostat since its in a bathroom and will get to hot without it. The directions call for a line voltage thermostat, but I was having trouble finding one that would work with my unit since the K42 only uses about 30 watts to run the fan, the heat comes from hot water. I would like to use a heat only 2 wire 24 volt thermostat and use a relay like RA89a From Honeywell. will this work or is there a better option? Running electricity for a line voltage thermostat is not preferred. Thanks mark

Jamie Hall

Your option should work. Note that you will have to run a 120 volt circuit -- line voltage -- to the relay anyway, so I'm not quite sure what, if anything, you are gaining. You will still get a little heat from the kickspace heater anyway, but it won't be that much.

Sparkie212

I already have the electric in the crawl space run and hooking up a relay would be simple, Running the conduit trough the wall would require a larger hole for the box and then more drywall and painting. I did not know if the RA89a would be overkill or if there was a better option. I have a few of the RA89A's already to control the pumps for my boiler and at times I have a bit of a humm and would like to make sure I install something that is quiet.

hot_rod

plenty of line voltage thermostats available. Look at any of the electric radiant heat manufacturers.

Sparkie212

thanks for the screen shots of thermostats.

Sparkie212

I did the installation with a 2 wire heat only thermostat connected to a Honeywell RA89a and mounted the RA89A to a 2 x 12 floor stud and it works fine but I get a humm when activated, I tried putting a piece of rubber behind the RA89A and still get the humm. Is there any way to get rid of the Humm or should I have used a different relay?

hot_rod

Yeah, some transformers make a humming sound, maybe try and isolate the mount somehow.

EBEBRATT-Ed

@Sparkie212

Funny you mention that freiking humming. I had a RA89A on my boiler for 40 years no problem. The relay quit and I bought a new one same thing......looks the same too.

But the new one hums. I read in the paperwork that Honeywell says to mount it on rubber. I ended up changing the boiler and sold the house and didn;t use the relay.

Pisses me off because honeywell has been making those relays for years

Jamie Hall

May I say -- drawing on the high fidelity sound side of my life -- that building a transformer which doesn't hum is really remarkably difficult, especially if one is trying to hit a price point.

Sparkie212

I did try and isolate by putting rubber behind the relay and no help. Not sure what else would help. The RA89A is in the crawlspace and I can hear it on the main floor. I do have a few real old RA89A's on my boiler and they are not that noisy. The Taco relays say if there is hum they supply resistors that are supposed to help, I dont know if that is possible on the RA89A? Taco is saying that some power robbing thermostats are a culprit. My themostat is not programable but digital also has two batteries. Is there anything I can do to get rid of hum?

Jamie Hall

Be sure that your mounting for the relay is actually vibration isolating. Just putting rubber behind it won't help -- it's the mounting screws or bolts or whatever. You need to create a mount which has no solid contact whatever between the relay case and whatever it's mounted on. Something like a mounting plate secured to the substrate and the relay secured to the mounting plate with nuts and bolts through rubber grommets in the holes in the plate.

Sparkie212

Is this what you had in mind?

hot_rod

Try temporarily hanging the relay by a wire or something just to see if it eliminates the noise issues to an acceptable level . Suspend it with some perforated plastic plumbers tape

Or get a different relay.

Jamie Hall

Sparkie212 said:

Is this what you had in mind?

Exactly.

Sparkie212

Thanks for all your help I will try and isolate the relay and see if that helps.

Sparkie212

Well I isolated the RA89a and I still get the hum. I got a hold of Resideo(honeywell) and they recommended me sending unit back for refund with no recommendation for replacement. I just assume that relay is going to hum. Any suggestions for another relay or solution to my issue? I saw another relay the Taco Sr501-4- not sure if that will also hum. ??

hot_rod

Sparkie212 said:

Well I isolated the RA89a and I still get the hum. I got a hold of Resideo(honeywell) and they recommended me sending unit back for refund with no recommendation for replacement. I just assume that relay is going to hum. Any suggestions for another relay or solution to my issue? I saw another relay the Taco Sr501-4- not sure if that will also hum. ??

Hard to predict which transformer will hum, I think it is more about quality, not the brand name.

We had transformers built to a tight output voltage spec for the snowmelt sensors we sold, like this one.
Direct plug in transformers built into a case like this tend to be 100% silent. Typically used for door bells, alarm systems, etc.

Sparkie212

I can live with a little hum but the Honeywell seems excessive. The real old Honeywell ones I have are pretty much silent, not so with the new ones

Dave T_2

get one of these, it won't hum
https://www.supplyhouse.com/Taco-SR501-4-1-Zone-Switching-Relay?gclid=CjwKCAiAiML-BRAAEiwAuWVggnRyk0zAm7VNfR1TpWj_DVV-wazBO2Q6gusqjyW40m-0udoH82Uz2BoCf5EQAvD_BwE

Sparkie212

Thats one of the ones I was thinking of replacing it with. If you have a question you can actually get a hold of someone at Taco also which may or may not be helpful. - Thanks for the suggestion.

Sparkie212

Replaced with the Taco 501-4 and working just fine, Thanks again