Tekmar 665 operation

PinkTavo

Hello. I just modified this post after looking back over the Tekmar document.

I have a job with a Tekmar 665 specified for snowmelt. There is a heat exchanger dividing the load and system sides of the overall system. I have the system pump (P1) wired to start from Terminal 11 and the load side pump (P2) starting on heat at Terminal 15, with a freeze protection aquastat in series. The question is: How is thermal shock of the slab mitigated, when the system supply temp is 180 DEGF...and likely the load side is close to that temp after the HX? It doesn't seem right to be flowing such warm water thru the slab. I understand that the heat contact (Terminal 11) cycles on/off, but that would still not account for what would seem to be too high of temp going to the slab. Thanks for any insight.

the_donut

Depends on size of slab vs delivery of btu in. A large slab has a large thermal mass to overcome. It would have to be a lot of heat pumping into slab to make difference. Picture soldering iron vs dry ice. The block of dry ice can more than handle that 600* iron because of the difference in thermal mass.

Zman

The 665 is a pretty basic controller. Since it does not read boiler, or even water temps it will not be able to do what you are asking.
The higher end models will give you the control you are looking for.