Tekmar 262 control

Matt_8

This summer I redid my hot water piping in my house. i ripped out the old gravity fed lines and zoned 4 zones in reverse return. I fired up the system the other night and it works very well. It's the first time in 6 years that I have even heat at all radiators.
I put in a Tekmar 262 controller (2 stage - I have a Wood/coal boiler with my oil boiler) and I put in an indirect water heater. I put a high limit aquastat on my oil boiler but have no low limit. What I've seen can happen is if there is a long delay for heat or dhw the boiler will cool down significantly. Is it necessary to put a low limit on the boiler to keep it at say 130 degrees? I have a bypass in the piping for return temp while its running, but that doesn't do anything to keep the boiler semi- hot at idle. The boiler is a steel tube EFM. On my outdoor reset minimum I have it set for 140 but it would be nice if the controller would control the boiler temp at idle so it doesn't dip so low (it goes down to 100 degrees sometimes)
By the way I really enjoyed this heating project. Just ordered insulation for all the piping. 520' - 3/4,120' - 1", and 50' - 1 1/4. I am an electrician by trade and this heating stuff is really gratifying when its done right.
Thanks for any responses to the low limit question. Matt

clammy

low limit

what type of fuel is it burning gas or oil you might try a dual aqua stat controller with a high and low limit on oil units i usally use them to keep the boiler warm helps to keep the boiler clean on gas i rarely see low limit aquastat only on older unit that had tankless heater but i have to say i've boiler with the tankless removed and the low limit still working on boilers 70 to 90 years old in good shape while i've seem the same units with out them totally shot i firmly believe that a low limit aquastat does prolong the life of a boiler even though there,s a loss in fuel comsumption.it's a toss up every bodies different thank god i believe on oil it is necessary other wise be prepared for lose of eff between cleaning and replacement of combustion chamber every 2 to 3 years if your lucky good luck

Joe_13

WWSD set?

I think warm weather shut down (WWSD) will ignore min boiler temp when set. Turn this setting off and lower the boiler min setting durring the summer is a cheap solution I think. There's a lot of options on the 260's.

Eric Paro

262

I would let your boilers go cold,if you must maintain temp. then turn your tekmar minimum temp setting to your selected min. temp. it will still maitain temp. even during wwsd. The 262 is a wonderful control and I have installed it many times, in fact I use a tekmar control of one sort or other on every job i do and they have yet to let me down.

Matt_8

I have the minimum already set for 140. Correct me if I'm wrong ,but I believe according to Tekmar's lit. that the minimum boiler setting is the lowest target temp that the unit will use when in reset mode. In wwsd the boiler min. does not apply, according to what I've seen so far. I have been running in wwsd for about 2 months now with an indirect water heater and the controller doesn't seem to care about the boiler low limit. I wish it did because if it dips too low my old tankless coil begins to weep at the flange nuts!

Steve Eayrs

I would install a limit stat,

.....or a triple aquastat for the operating aquastat, with the low setting 130 or so. This should be warm enough to respond fast enough for the in-direct, but of course that will depend on the size of teh heat load, btu and mass of the boiler, and other things unknown.

The tekmar can still take over, whenever the temp. goes above what you have the aquastat.

Steve

Joe_13

If you're using a tankless coil, there's no point in having WWSD set making it a cold start boiler in the summer. Just set min boiler temp to 120 degrees durring the summer months. Think anout getting an indirect. It's a shame you can't use all the extra features of the 262 like priority for an indirect, post purge, etc.

Matt_8

Joe,

I have an indirect already. I unhooked the tankless coil. I thought i mentioned that in an earlier post. The reason I got the 262 was for all of its features for my application(2 boilers,dhw,etc...). I love this unit. I hooked up an 071 sensor for the dhw and I installed the remote readout module in my living room. It's nice to see so many variables at one time on the readout. So far the indirect is working great! It looks like Tekmar has an advanced, quality product and experience to back it.
I used relays for the zone control (4 zones + dhw) but I saw that they make a 368 zone controller that will piggyback on the 262 10k terminals for zone control. I might do that for next year. They aren't exactly cheap, even at wholesale! Matt

Joe_13

I got confused Matt

when you mentioned the tankless coil bolts leaking! Thought you had it hooked up to a storage tank. I agree 100% on the Tekmar's. I still think they can do everything and more a Logmatic control from Buderus can do for half the price.