Controls question

Glenn Sossin_2

I have used Tekmar on 2 stage heating (1st radiant) (2nd Geothermal) with 2 stage Geothermal AC. I believe the tekmar 546 thermostat has the ability to fill your requirement/

Agree with Al. The local tekmar rep should be able to guide you. Make sure you have a good electrician. Not very tolerant of mis-wiring. Can drive you crazy trying to troubleshoot.

Randy Calvi

Temperature/staging controls - suggestions?

Can anyone recommend a control arrangement/brand/system that will allow 2 stages of heat, 1 of cooling, auto changeover AND stage rotation of 2 geothermal heat pumps with outdoor reset?

System will have radiant floor (SOG) for first stage heat with 4 pipe hydronic air handlers for 2nd stage and the same 4 pipe units for cooling. Takagi TKD-20 will handle the higher temps. required for the 2nd stage.

I'm looking at the Tekmar tn4 stuff, but I can't see any way to stage the cooling that's doesn't involve a separate controller). It'd be nice if I could get something like a 261 or 262 reset controller that had autochangover and cooling setpoints. Web searches have not revealed any 'killer apps' for me, so I'm asking here. I'm not opposed to PLC's if someone can recommend one.

Thank you in advance - I appreciate the input.

Randy Calvi - The Heat Exchange, Inc.

Al Letellier_9

controls

You're on the right track with TEKMAR. Sit down with your local rep and have him set you up. That's what they do....

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eluv8

uponor/wirsbo control

Check out uponor/wirsbo, they have a control similar to the tekmar. From what I understand it can be programed to do anything you want it to do. I have heard good things about it once it is set up and running. Internet access from the office capable, for diagnostics and troublshooting.

Al Letellier_9

controls

Wirsbo controls......have you checked the price versus TEKMAR for virtually the same control.....OUCH !!! And it is made by TEKMAR

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Randy Calvi

Tekmar thermostat is fine...

for the wall stat and the one I planned on using. The problem is doing staging and changeover control of the heat pumps. Two identical 4 ton water-to-water units that will run in heating and cooling. The Tekmar 261 reset control will do just what I want in heating, but not cooling. A controller with 'auto changeover' similar to the thermostats' but also with the ability to stage and rotate the two heat pumps would be ideal.

The Tekmar guy has a solution, but it involves having separate heating and cooling controllers with reset only on the heating side (OK). But that means either I don't rotate them in cooling OR I need to have an independant rotate timer (which I ALSO can't find!!) Using two standard two stage temperature controllers and a transfer relay going through a rotation control would be acceptable too I suppose.

I could build something by cludging enough relays and controllers together, but I'm starting to like the look of my installations that don't have all the duct tape and baling wire hanging off the wall. Anybody know any PLC's with dry contact inputs and programmable dry contact outputs?

Anyone?

Anyone?

Bueller?

Uncle E J

Lead Lag

Randy, We use an electronic Lead Lag control that is fully adjustable for your two units in cooling/heating. Check the website for BardHVAC, and Marvair. EJ

Uncle E J

Telecom

Randy, The Bard unit is the MC3000 and the Marvair control is the ComStat3. EJ

Randy Calvi

Thanks EJ

Those look like they might be what I'm looking for. I'll let you know what I figure out. (Now if I can only get some time to do that.)

Thanks for the help.

RC