Need a simple outdoor reset
I would like to install on outdoor reset to control the temperature in my radiant water heater. It’s a Weil-McLain CGa PID, which comes with an adjustable temperature limit switch that I would switch out. I’ve already got a zone controller.
Anyone have suggestions for a make/model & an online source?
Based on your description, waddaya mean by a reset?
You might be able to get ahold of the manual for the PID controller that OEM'ed to McLane, that'll give you more information thn you'll ever need about interfacing.
If you're looking for possible online sources, try:
which is McMaster-Carr --I love this company!
http://www.newark.com or http://www.jameco.com --for any electronics component under the sun.
or for the HVAC approach:
http://www.johnstonesupply.com -- which has a website that makes it impossible to find anything but their catalog is great!
I can't really comment on your specific application, but Tekmar makes all kinds of outdoor reset and boiler controls. None of them are exactly "simple", but they do work. A word of caution, though; there are a variety of factors to consider when resetting boilers, one of which is whether or not the boiler is capable of accepting lower return water temperatures and not suffering damage from condensing the flue gases.
What are you using, baseboard or infloor?
Funny how well bumps work...Thanks Plumbbill
To answer the questions posed this morning:
Jason D:Reset = reset thermostat, which would vary the boiler's temperature setpoint based on the outside temperature - colder outside = hotter water to radiators.
The interface is simply a 120V switch loop - the existing one works exactly like the old dial-type wall thermostats: A switch is closed in the loop when the water temperatue is less than the setpoint, and then opened again once the temperature is satisfied. Also in the loop - in series - are a spill switch and rollout TFE.
I will check those sites; Thanks!
NPitz:I found the Tekmar site and found at least one controller that would work, but it also has bells and whistles that I don't need (or need to pay for). I was not able to find a distributor online anyway - maybe one of JasonD's suggestions will pan out though.
As far as the return temperatures, mine calls for a minimum of 130°F, so I will probably limit the setpoint to at least 150°F. However, if I can't find a simple reset, I may consider installing a bypass loop.
rich1:I have radiators - and a water coil in my air handler. This is the first winter with the coil, so I'm going to have to do some experimentation: The ductwork is zoned, but the radiators are not. I'm considering buying zone valves, but will probably not do it. More likely I will just cut back flow to the radiators.
Thanks to everyone-
"Need a simple outdoor reset"What you need is a model #w.i.f.eThis unit checks the outdoor temp once an hour and then sets the water temp for the boiler.
I thought the w.i.f.e. unit checked the indoor temperature once an hour and adjusted the thermostat for the house.
Danfoss Model ECL 100 is as simple as they get.
Contact Brian Wheeldon at Danfoss Calgary, 403.236.9560
If your boiler has electronic controls, the outdoor reset is usually just a thermistor mounted in a housing that can be attached to a soffit or gable. Why not contact the boiler manufacturer and get the real thing? They cost $50-$100.
Exactly- I need a Weil-McLain BCP-3, but it cost $683 for the one online supplier I've found. It's not worth the investment unless I can get what I need for <$100.
The boiler has electronic controls, but this portion of the system is simply a mechanical (spring-loaded?) thermostat that opens and closes a switch in the gas valve loop based on the water temperature.
I'm investigating prices on the ECL100 per RBean.
It sounds like the Well-McLain needs a separate controller to implement the outdoor reset function, and that's probably why it's an expensive option. Other boilers already have the smarts built in to their control boards and only need the simple external thermistor to make the outdoor reset functional.