Help with Tekmar system rebooting itself randomly

zyx330

Hi all, I am looking for some advice on dealing with my Tekmar system (used for floor heating in my house) randomly restarting itself. The system (Tekmar house control 403) and the main thermostat (Tekmar thermostat 552) reboots every 2 - 10 minutes. It turns off for just a second, comes back on, and then takes about 30 seconds to read the signals from all thermostats again.

Some additional context:
1. It's hooked up to 7 radiant heat zones
2. As far as I can tell, all of the zones are functional... they can all call for heat okay and they do warm up the house
3. The problem does seem to become a lot more frequent when I adjust the temp on any of the thermostats (i.e., causing it to either start or stop calling for heat)
4. There was this weird error message "Dev Lost 1:20"...which is strange because I don't have 20 devices and none of the thermostats have that address

Pictures are attached.

Thanks in advance!

Jamie Hall

First thing I would check is the adequacy of the power wiring to the units. All connections solid? That sort of behavior often suggests a momentary power drop out.

zyx330

Thanks, Jamie - do you mind giving me some guidance on how I might be able to check that to narrow down the cause? I do have a transformer in the boiler room that is powering the tekmar and the expansion

Jamie Hall

First, make sure that the wiring to the primary of your transformer is sound, and that it's correctly grounded.

Then, in your photo, I see a grand total of 19 wire nuts (I may have missed one or two). Any one of those could be suspect; I take a rather primitive approach to wire nuts: I hold the nut and then pull on the wires both together or separately. Obviously, they shouldn't come apart... Also, I'm not really too keen about the look of the connections to the transformer; they should be checked for security as well. Then I would open that junction box and check the connections in there as well.

neilc

7 thermostat, 2 temkar boxes,
I assume 7 valves,
what's that trans rated for ?
it might be tapping out,
add up all the load(s),
and maybe beef up the wire from the trans to its first stop,
it, the wire, might be warming up also.

zyx330

Thanks, neilc... are you thinking perhaps the transformer does not have enough to power all the thermostats & tekmar boxes? How do i find out the load required for each thermostat & tekmar?

And, what do you mean by the wire might be warming up?

Thx again!

neilc

the temkar manuals should spec what they draw, the valves too,
I'm reaching there a bit but it's worth looking into.
and if i'm right, then you might be loosing some volts and amps in the small wire between the trans and its first stops(temkar?)
gotta read all the labels

Jamie Hall

What @neilc means by the wire warming up is that that first brown wire from the transformer looks as though it could be too light (the white one I can't tell). If it is, and your collection of gadgets draws close to the transformer rating, it could be quite literally warming up. Which might also mean that you are losing a good bit of voltage along that wire -- possibly enough to make the equipment drop off line.

neilc

I may be off base on the voltage drop thing,
and I think Jamie is right about finding a loose or intermittant wire or device,
check out pg 30
http://www.tekmarcontrols.com/images/_literature/403_d_07.pdf?lbisphpreq=1