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[smithbr]

Grr
No problems at shutdown last spring.  Fired up the furnace today, and A-1 error.  Changed out TC, as I had been warned this was a common problem.  Same issue.  Cleaned connector in airbox, no luck.  WTH?  This thing is 3 years old, the TC I took out looks new, and isn't the problem anyway it seems.  The TC cable runs uninterrupted from there to the back of the control panel, where it snakes up into the panel.  No water apparent in the airbox.  Power cycled the unit many times, no effect.  I'm stumped.

CAN THE UNIT RUN SAFELY without the reaction chamber TC reading?  I'm getting last spring's last reading from my wifi module (190) (but the circulating water is cool to the touch) so its confused.
Blair

[smithbr]

Bigger problems.  Water temp shows as 32.  pipes now warm to the touch.  My bet, control board failure - might have been lightning strike this summer.  Sigh.  On Friday night, of course.  With -9C (15F) forecast for Sunday.  Now, decision time.  Since I can't tell water temperature, can't tell reaction chamber temperature, do I kill the fire and drain the 200 gallons of water to avoid freezeup, keep the fire minimal to heat the water just enough to avoid freezup, or do I allow my propane furnace to (hopefully) backheat the CB water until next week, when someone might answer the phone at Central Boiler?
Opinions, anyone?
Blair

[Roger2561]

Man, that sucks!  I wish I knew the answer whether or not it's safe to run with a faulty TC.  Is there a way that you can keep the OWB water circulating without it back heating through the propane?  I put isolation valves on the pressure side of the Hx so that if there is a problem with my OWB I can keep the OWB water circulating through the Hx without it putting a strain on the propane (mine oil).  As long as the water is circulating it shouldn't freeze.  Roger 

[smithbr]

Roger
Reality is, I wanted it set up that way so that if I went away for a day or more, and we went FO, the loop wouldn't freeze regardless; great last ditch defense against -30 weather if a car accident were to take us both out of action, but not so good in this slightly less critical issue.  I have a second layer of defense, if I valve in my hot water leg but leave the hydro on for the hot water heater - but that one will cost oodles, I know.
I'll just let it circulate, and light a small fire mornings and evenings to help with the heat content.    Monday, we can start to sort this out. 
The bypass for the hx in the furnace is a good idea too, but I don't see a strong reason to retrofit it unless I have to replace the HX, so I can worry about it then.
Blair

[smithbr]

Thought about this a bit more before sleep overtook me.  What I observed before I pulled the fire last night was that the furnace seemed to kick into stage 2, then stage 3, while it still said the TC was toast, and the water temp was 32.  I presume that the controller attempts stage 2 and 3 based on a timeout of some sort, even if the reaction chamber doesn't reach the temperatures needed for the stages(or is flagged as bad).  So if we hadn't also had a bogus water temperature, I think the system would have limped through the night, keeping the water temperature in the setpoint range of 180-190, but with poor efficiency.  I'd have been okay with that.  But the death knell was the water temperature stuck at 32.  Without that feedback, the system will just boil the water away.

The water loop temperature, with the circ pump on and the propane system heating the house, seems to be around 35 C.  I shut the circ pump down for the day (it's 0 out there now), and we'll see what the temperature is at sundown.
Blair

[boilerman]

Keep the pump running! Also with a TC fail error on a CB gasser it will fall back into a timer mode for stage 1,2 & 3 air like their early Eclassic 2300 did. It should not boil, overheat or go out if a TC error is showing. I believe you might lose a little efficiency but hey no other brand gassers are fine tuning secondary air based on thermocouple combustion readings, so fire it back up and run until you get a replacement thermocouple.

[Roger2561]

That's a good piece of info. to keep under my cap for the just in case scenario. 

[smithbr]

Boilerman:  but How?
Remember, I seem to have both a TC error for the reaction chamber, and a goofy water temperature (32).  So what will the fallback mode do about knowing when to run?  It has no idea of water temperature.
Confused
Blair

P.S.  Also not sure about the pump loop - doesn't the thermostatic valve effectively stop flow through the house side until the water is much warmer than I'm seeing(90 F)?  If that's the case, the outside loop won't ever see water heated by the propane furnace, and the only thing warming it is the heat of the pump itself.

 

[smithbr]

Boilerman
I see back in 2015 you suggested the TSV wasn't a go/nogo, but rather that even below 150 it did allow some passage to the house side for reheat.  Do you know if that's the case with all TSVs?  The description in CB's manual for the 1450E is pretty stark, it describes three modes.  when cold, it depicts the flow as totally returned to the furnace.  I'm wondering if that's just manual-speak, or if the TSV supplied with the CB actually does totally cut off the house side when it gets cold enough.  I'm likely to pull out that TSV anyway in a few days, but for right now I can't work on the plumbing as I haven't got the necessary bits in hand to bypass it.
Blair

[Roger2561]

Blair - Can you bypass the TSV with a washing machine hose?  I installed drain bibs on either side of the TSV so if the comes that I need to replace or service it I simply bypass it without having to shutdown my OWB.  It runs like this;  pipe from outdoors to drain bib to isolation valve to TSV to isolation valve to drain bib to pipe continues to the next unit in line.  Make sure you shutoff the isolation valves or you'll have a very hot mess on your hands.  Roger 

[smithbr]

Roger
Without changing stuff with parts I don't have, no.  As I posted elsewhere just now, we made it through the night, and the water is holding in the mid 80's (F).  So the "trace" flow in the TSV must be fairly substantial.  I'd love to be sure it isn't just stuck open, and that it will always work this way, but that much faith is hard come by.  So sooner or later I'll rig a bypass, or toss it altogether.  But I don't have the time or energy right now to muck with it much, as long as I can limp along until I can get the OWF up and running.
Thanks for your responses, Roger, they keep me thinking about alternatives.
Blair

PS I've been mixing C and F temperatures in previous posts, which may have led to some confusion.  The water temperature stuck at 32 is F, not C, so there's something really wrong with that reading.  Especially since all the circulating water is around 30-35 C (85-90 F).  We'll see what CB says on Monday.
Blair
 

[smithbr]

Update - both TCs were fine.  Swapped in a new controller (Thanks, North Star!), and we're warming up now.
Thanks, everyone, for your feedback and suggestions.
The trace flow on the TSV was enough to keep the loop in the low 80s for the last four days, despite one night around 15 F.  That's good info, too, as if we had to be away for a few days, I'd not worry as much now.
Blair Smith