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Setback Thermostat for Radiant Heating - - Recommendations

4 replies [Last post]
Joined: Jul 1 2003

I will like to install a setback thermostat with varying tempurature settings for different times of the day, etc..

Because Eichler radiant heating systems are finicky (and I don't have a operating manual), I am reluctant to do anything without checking.

(1) The boiler is a AO Smith unit (original, I think) from 1973.
(2) I have copper tubing, and a simple Honywell manual thermostat. I think the power transformer is exposed, next to the boiler.
(3) Any recommendations on manufacturer, (or avoid a particular type or manufcaturer?)

Also, would appreciate simple instructions and precautions in removing the existing Honeywell, and replacing it with a new one. I afraid of turning off anything relating to the system and not be able to safely turn it on without calling in Anderson or someone else.


Joined: Mar 20 2003

our heating/plumbing professionals had discouraged the idea of using a varying temperature thermostat when we moved in here (that's what we wanted to do as well). Their thought was that the radiant heat is not as quick to respond or as efficient as true heaters, so the changes in temperature could be delayed and felt differently by the resident, as well as possibly waste energy in the end. Did your plumbers say otherwise? I just listened to them because they fix a lot of the Eichlers in our neighborhood and I figured I didn't know anything about boilers. Please let me know if you know something different. Thanks!

Joined: Mar 22 2003

Our radiant heating specialist installed Honeywell units for us - Model is Chronotherm IV Plus. We have 4, and they are terrific. FYI, we are no longer using the radiant system, which was disconnected by the previous homeowner, but our boiler is still going strong and is connected to a baseboard system.

Also, with these you can adjust the acceptable amount of deviation that is allowed in the temperature, so they are not constantly turning on and off. We found ours pretty easy to program, with a lot of nice features, such as "daylight savings" (so you don't have to re-set the clock) and "hold" (what we use in the summer months).

We trust our radiant contractor completely, as we have been working with him for 8 years and he is wonderfully skilled and has been doing this full time for 20+ years now. These are the thermostats he recommends for anyone wanting these features and he has installed a lot of them in Eichlers throughout the Bay Area.


Joined: Jul 1 2003

I'm not a do-it-yourselver or home mechanic, but things have to make sense to me. Your heating plumber, I think, is correct about how a radiant system responds, but I don't agree that a setback thermostat isn't useful. True, radiant heat is slow to warm because it's indirect heat so temperature drops are not quickly compensated like forced-air heat; my intended use of a thermostat is to reduce the setting (i.e., practically de-activate) when I wake up (the boiler is often on at 7am), and quickly activate a vacation or away-from-home setting. However, the use of a setback thermostat, in my mind, is different than how a radiant system performs. Whether it's slow or fast to warm does not effect whether you want different settings at varying times.
Before our 2-year was born and when I lived on the East coast, I used a setback thermostat to schedule literally 3 WINTER temperature settings during 24-hours: at work (55), at home (72) and sleep (65); and separate weekend settings. For A/C, the same themostat would provide similar setting flexibility.
However, on the West coast, the least expensive and flexible thermostat should serve well for heating because heat is needed only at night.

The problem I am encountering is whether I can turn off the heating system and install a thermostat and not have to call a professional to turn it back on, and also understand what precautions to take. (For example, as a precaution I disconnected the outside phone jack when installing a new phone jack to avoid static or low voltage shorts inside the house).

Joined: Mar 20 2003

thanks for all the good info. I think I will get a second opinion from another plumber...

BTW, my husband changed out the thermostat and had no trouble or need for a professional when turning the boiler back on. But knowing him he probably never bothered to turn it off and just took his chances! :)

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