Tekmar 2 stage control

tim smith_2

Any one used a 262 Tekmar to control a lo hi lo power burner on a commercial boiler. Got an old Kewannee firetube with a Webster lo hi lo burner that i am re- controlling. 50 unit bldg with fin tube convectors. Looking at resetting temps between 140 and 180 degrees. Anyone's comment would be appreciated, Tim.

Boilerpro_3

Absolutely great control

however, I haven't used it on that particular application. I used it with two single stage boilers (low mass cast iron) that are provided with return temp protection (either Esbe thermix valves or Variable speed injection), some with feedback from a tekmar 369 zone control.

With this application, supply temps can modulate fully and the control takes full advantage of this by running on the first stage as long as possible, sometimes with a observed
differential as high as 60F, if I remember correctly.

With an apartment structure, there are very large internal gains, and since the heating system is sized for no internal gains, typically you need alot cooler water temps than you'd expect and much lower boiler capacity. Add to that typical oversizing methods for both radiation and boilers and you may find that the boiler will heat the structure in the coldest of weather at 140F on low fire only. In this case, you don't need the control.
Before installing the control, you want to find this out. I would try to install boiler protection so you can use full reset, as this really limits tenant abuse of "Free" heat. If you set ths heating curve tight to the actual load, people who leave windows open in the winter, storm windows open, crank up the heat to 85F, will the disappointed, becauae the system will only produce enough heat to keep them at 70F or so under proper conditions. Windows left open will make them cold, and a thermostat set to 85F will never get above 74 or so, on a typical system.
Using full reset puts about 85 to 90% of the control of the heating system in the owners hands, and the thermostats only serve to limit temperatures on especially sunny days or other big internal gains.

Boilerpro

tim smith

Tekmar

Boilerpro, thanks for the reply, the only problem with doing full reset is the piping is 3" and mix or injection will get cost prohibitive. Would love to but I don't think that's in the cards. Thanks again, Tim.

hydronicsmike

Tim...

...did we get you looked after yesterday? If you have more questions, pelase call us (tekmar) back.

Mike

Boilerpro_3

Some reasonable cost options for full reset

I'd first check your actual load and design temp. If your convection is designed for 180F supply and your boiler can run 200F supply, you just cut your injection volume in half by running 40F delta tee across the injection loop, instead of the typical american system temp drop of 20F. Using this method, you can carry about a 1,200,000 btu/hr (60 gpm injection) load using a single tekmar injection control powering dual B&G NRF-33 pumps. That kind of output can probably easily handle a typical structure up to 60,000 to 80,000 sq ft.

Boilerpro

Boilerpro_3

Mike is the Man! NM

hydronicsmike

Dave...

...you are too kind.

See you in Boston?

Boilerpro_3

Nope

Blew my wad on the Baltimore trip!

Boilerpro

hydronicsmike

sorry to hear...

...you will be missed!

Weezbo

hard to fault injection Tim....

pump sequencers..... wouldnt hurt to ask...guy might like the numbers every month.

tim smith

Thanks guys for all the reply's.