oil furnace runs for two sec

jjfarm

I bought this home in Jan 2011. It has a  Burnahm  oil fired furnace hot water baseboard w/tankless water. Just one aquastat (none for the coil so no control on the domestic hot water temp). I have three recirc pumps with an Argo  861-3 relay. I have all new digital thermostats. Maybe a dozen times a day the furnace will come on for maybe 2 to 20 seconds and shutoff.  System is probably 12 years old.  This situation doesn't cause a problem but it is frustrating and will most likely shorten the life of the furnace and its appurtenances. As we don't heat the upstairs I am in the process of swapping out the relay cubes, leaving one out, to see if there is a bad one. Any opinions are welcome.

Thanks

Jamie Hall

This may be a dumb question, but...

did it do this before the new digital thermostats were installed?  If not... well... I'd start by testing them, one at a time, to find the misbehaving one.

icesailor

Short Runs:

You shouldn't have a single acting high limit on your boiler with a tankless. How did you get such a boiler fitted with a tankless with this control or did someone install it later?

Your digital thermostats may be having a dispute over who is controlling what with the boiler and the Argo.

Post pictures of the front of the boiler and showing the control.

It shouldn't be like that.

jjfarm

thermostats

Yes, the problem was occurinng before the new thermostats.

Don't disagree the thermostat could be antagonistic to each other and the Argo.

I have set each stat, one by one, down to the lowest setting but it made no difference.

This 861-3 does not have a prioity sw as I see the newer ones do.

Granted the the original wiring could have a glitch, eg: neutral not consistent, wear spot on a wire, etc.

After removing the number one cube and and pulling the number three cubeand putting it in the number one socket and leaving out the number three socket empty (the number one cube is on my desk) I have yet to notice the "two second" problem.

So if I am lucky I had a bad cube in the number one socket. I will put it back in the number one but still leave number three empty and see if the problem comes back.

jjfarm

short runs

Here are several pics. I don't see a temp control for strictly the coil??

billtwocase

short cycle

The zone that has no relay will now have no heat. It could be the thermostat causing this. Also, the LO limit is for your coil. The boiler will maintain what the low is set for. The HI limit is just that. The burner will turn off at that temp when there is a call for heat. I see they have wired this for ZR-ZC. That was a plus. Try connecting the thermostat to another circuit. Remove the T-T wires, and try it. The heat will not go to that zone, but it may help to troubleshoot the thermostat. Also thermostat location for that troubled zone?

Paul48

Aquastat

That is a triple aquastat. It will maintain the boiler at the low limit setting, so the coil is always immersed in hot water.If you run a hot faucet, the boiler temp will drop, and in your case, when it gets to 160* the boiler will fire.Do you have a flow control valve on the supply above the boiler?







                                                       

jjfarm

flow control

Aquastat,

I have flow B&G control valves on each circuit.  I'm not sure but the picture you sent doesn't look like an aquastat it looks like a flow vontrol valve. Not sure how I would pipe in the object (in your pic) to the domestic hot water. Wouldn't that put house PSI in the heating system?

jjfarm

Thermostat

Hi short cycle, thanks for your help.

The stat for the #3 zone is for the upstairs and is in the mbdr and not near a radiator. It is brand new, so as the problem has been before the new stat I kinda ruleout the stat. Good point about putting the cubes back to orginal spots and taking off the #3 stat wires.Troubled zone? Can't say there is a troubled zone. 

We try not to heat upstairs, 5 rooms and a bath but we keep the temp set at about 55. Never realized the low limit was directed at the hot water coil but I must admit I don't understand how it knows the difference between the domestic hot water temp and the boiler temp. Always thought the heat in the boiler water was transferred to the coil.

Again it appears I have had no "short cycles" since I swapped the #3 cube with the #1 and left #3 empty.

Oh crap!

Just as I am typing this, at 12:12pm, the furnace did it's two second thing. Perhaps so much for a bad cube! This was the first time in over two days I noticed this and I am inside a lot. Retired.

Maybe it's time to look at the aquastat. Or just put in a new 861-3 relay system, could be a finicky diode or a crack in the printed circuit that opens or closes depending on ambient temp. I believe the 861-3's are about $100.

Hopefully I get this resolved before warm weather gets here LOL

Paul48

Clarifying

"Always thought the heat in the boiler water was transferred to the coil"

  It is.....technically it's being transfered to the DHW in the coil. That heat is then taken away with the water,lowering the temperature of the boiler.The boiler will then fire to try to maintain the low limit setting.

  Sorry for the confusion. I was attempting with my first post to clarify what the aquastat in your picture was, and how it worked. I then asked about flow controls, with your ghost cycling in mind.Without flow controls, you might get a convective flow of hot water up and out of the boiler. This would cause the boiler to run much more frequently(than normal) to maintain the low limit.

 



.

Jean-David Beyer

What is that piece of metal at the output of that 222?

I have a model 221 (1 1/4 inch) flow check valve and it does not have that piece of metal. Yet from the green paint that seems to be on it, it left the factory that way.



What is it for?

billtwocase

shipping

That is a piece of cardboard for shipping only to keep the weight from slamming against the seat until it is installed

billtwocase

I must say

Argo is not my favorite. I would consider replacing it. Chances are that when one or all the zones call for heat, the Z-R circuit is making and breaking. I would consider Taco

jjfarm

short cycle

I seem to be running out of bright.

This system is setup so whenever a thermostat calls for heat the boiler kicks on.

So yes, if a stat(s) calls for heat and if a relay trips in then out the boiler would shut off. That should leave the stat still calling for heat. I don't know what would happen in that case.

Could be I am seeing two different situations.

One being with Z-R circuit makes/breaks..The otherwhen a stat calls for heat the boiler is right at the HI temp and only runs for 20-30 seconds. I am only guessing Would that happen?

I've thought of the fire-eye but it works. Although there could be a loose connection with it. For that matter anywhere.

 

I don't have any gravity feed problems