older Tekmar control system

Paul S_3

I recently received a call about a large residential hot water system that was experiencing control problems. A little background on this system. Home square footage is about 12,000 sq ft. There is about 20 low temp infloor heating zones and 2 high temp cast iron baseboard zones. and a 119 gallon indirect. Boilers are 2 cast iron direct vent water boilers. Control system now is Tekmar 252 boiler control/DHW, 371 house control (injection mixing for low temp infloor), 2 Tekmar 368 zone controls and 1 tekmar 367 zone control..... all thermostats are Tekmar rtu 055.... all controls are OBSOLETE.... General contractor called me once plumber and electrician couldn't get heat running..... home is being renovated etc etc etc.... I found about half the 055 stats at fault reading 0 ohms.... house control and 1 zone control is reading "internal fault error". Basically I have to replace the whole boiler control system. I really would like advice on what you radiant guys would do.... is there a benefit to Tekmar stats for infloor heating? would the system operate better with them? I'm not looking to repipe the boiler room or replace boilers..... boilers were changed just recently.... I was thinking of using regular circulator relays ( Like Taco (SR'S) or Caleffi ) with standard thermostats and just one Tekmar 374 control to stage the 2 boilers, DHW priority, and injection mixing for the low temp zones.... which direction would you guys go? ....Thanks Paul S

Zman

The new tekmar stuff is really slick. It takes into account, out door reset, indoor feedback and can compensate for some pretty inbalanced systems.

It also comes at a high price and has what can be a pretty confusing interface. Some customers hate the complexity and just want a t- stat. Others love feeling as though they are on the " cutting edge"

I think it comes down to the type of system and the preferences of the customer.

For the simple setup, I really like the wirsbo wt-1 t stat. It has some built in ability to control overshoots without the cost and complexity.

Solid_Fuel_Man

For the customer who likes the simplicity of a thermostat I like the Honeywell visionPro 5000 series and I tighten up the differential to 1 degree for high mass radiant. Has worked very well for me. You have to make a judgment call if there needs to be multiple Temps in the radiant of if simply one outdoor reset control will handle the entire building's radiant with simple wall stats on a very tight differential.

How is it zoned now? Manifold actuators, or zone valves flowing to zone manifolds? I have been replacing quite a bit of Tekmar controls as of late, seems 20 years if about the life expectancy. I do like Tekmar's flexibility and built in data logging for lead-lag boiler control etc.

The sky is the limit, but many/most times the sky doesn't need to be reached with this stuff, I find simpler works better. Tight thermostats I find work the best in most of my installs, I shoot for "nearly constant circulation" with air room stats.

Taylor

Paul S_3

No actuators.... zoned with circulators...Low temp zones are mixed down by variable speed injection...im going to give a price for pro5000's, Caleffi zone controls....and (1) 374 Tekmar....i would like to keep it simple....system hasn't worked correct for years customer tells me....

Turbo Dave

I have found indoor feedback from Tekmar thermostats paramount in achieving tight temperature control with radiant, especially in shoulder seasons and rooms with high solar gain. The performance improvement from the Tekmar communicating thermostats is substantial. The 532 is very basic. The 552 a high-end touch screen.

Tinman

12,000 sf rehab has to have some serious coin involved?

2 cascaded mod cons with low watt zone valves, buffer tank, and Delta P circ?

Paul S_3

I wish.....customer is doing a major renovation....general contractor had there plumber replace the boilers....they installed 2 190 k direct vent williamson boilers....i was called in after when multiple zones weren't heating....im just there to replace control system

Bob Bona_4

Good to hear tekmar is attempting to simplify. Utterly ridiculous in the past, down the the thermostats. I avoid them unless absolutely necessary.

Turbo Dave

The 400 series controls have everything you need in one control, up to 4 zones, with zone expansion easily done. The thermostats are now 2 wire also. My primary choice in controls, as we always have outdoor reset mixed supply temp in new installs. Much easier than the 1st generation to install, program and operate.

bthirsk

I just installed a Tekmar 374 to replace 2 older Tekmar controllers, a 353 and a 370. It works perfect for managing 2 different circuits with 4 zones, one a mass 1 and the other a mass 3. I would recommend to anyone.