Zone Problems with Boiler

heatwanted

I have a gas boiler HW heating system with a taco circulator pump for each zone that worked fine last season. When turning it on for the 1st time this season I found a problem with the boiler not running on one of the zones.

If I turn on the heat to zone 1 I hear the system actuate(clicks and such)and the boiler fires up and runs for about a minute and then shuts down. 

If I turn on the heat to zone 2 the system actuates and the boiler fires up and runs fine.

While zone 2 is running if I turn up the thermostat for zone 1 the circulator pump turns on and runs fine for zone 1. But, when I turn down the thermostat for zone 2 the boiler shuts down even though zone 1 is still calling for heat.

I attempted to figure a solution searching online and since it had an old/original S8610U Intermittent Pilot Control Module I swapped that out today with no improvement. 

EDIT   -    PROBLEM RESOLVED!
A shout out to user Intplm for having me look at the most obvious thing that I should have realized to do in the 1st place.

When I turned the thermostat up to call for heat in zone 1(1st floor) the boiler responded, ignited and ran for around a full minute each time. This made me just skip the step of checking the thermostat since a signal was obviously getting to the boiler.
The existing thermostat is a dumb, heat only Honeywell ct87k that is 5 years old. Since the unit was responding to the thermostat I figured it was a long shot but I followed the advice of Intplm and jumped the wires at the thermostat and the system not only responded and fired up, but it kept running normally. I just finished installing a new Honeywell ck87k that I grabbed at Lowe’s and the system is running fine.

Being such a rudimentary heat only thermostat I figured if the system responded and ran for at least a minute the comms from the Thermostat were fine.

Thank you all for your responses and help with this!

Mad Dog_2

Hiya ...where are you located?  We have some highly competent professionals here that may service your area.  Mad Dog 🐕 

Mad Dog_2

Need much more information and pictures.  That sounds more like an improper or loose connection from that problem zone to the relay.  Can you pull the cover off and send some pictures?  May be an easy fix..may not.  Mad Dog 🐕 

HVACNUT

It's not uncommon for someone inexperienced to add a zone and not wire it correctly. Was this zone possibility added at a later date?
Can you post some pics of the boiler and controls? 

heatwanted

The heating system is original 2 Zone from 1951. I have owned the house for 5 years with no issues or alterations to the system components. Both zones worked properly for the past 5 years. I am glad I decided to turn the system on just to make sure all worked well before the cold set in or else I would need to keep the basement(zone 2)running for the 1st floor(zone 1)to operate. Thank you very much for any assistance! 

Jamie Hall

At least you know that the pumps run when wanted, and so does the boiler. That's a step in the right direction. What doesn't happen, evidently, is that the zone 1 thermostat signal is not getting to the boiler. As has been said, bad connection, broken wire, ???

SuperTech

That's  definitely not a boiler from 1951

heatwanted

SuperTech - I did not mean all of the components were from 1951 - I was stating it was set up with 2 zones on the original plumbing install in reference to being asked if a zone was just added recently. Sorry for any confusion.

Intplm.

If you are able, go to the corresponding thermostat that serves the problem zone. Disconnect it from the wall and disconnect the wires. Jump or twist the wires together. If the boiler runs and stays on, you will need a new thermostat or the thermostat is not fastened properly to the wall/loose etc.
Also, check for a loose wire on the thermostat as well.

EdTheHeaterMan

There is a simple fix, I'm sure, but I need to know some stuff first.



Next is I need to know how the boiler was originally wired from the factory. Can you provide the model number?

EdTheHeaterMan

I believe that your problem is in the L8148 aquastat relay for 2 reasons.
1. I see nothing wrong in any of your other photos.
2. That is the hardest place to get to for repairs.




I have attached a Wiring Diagram of what I believe you have. There is a R845A circulator relay that is operating the first floor circulator pump. That is working fine but is not turning on the burner. Terminals 5 and 6 on the R845A are supposed to do that by connecting Z and R terminals on the L8148 aquastat relay. You need a TORX driver to loosen that screw on the R terminal and place a wire under that terminal. Since many HVAC and Plumber mechanics did not have those tools when your boiler was installed, that screw terminal may have been loose for years and finally, this week, the wire fell off.

By the looks of your photo the 5 and 6 terminals on the R845A relay have 14 gauge or 12 gauge wire connected to them. That means there is the same thick wire under those terminals on the L8148 aquastat relay. That wire can be low voltage control wire, but that thicker wire will do just fine. You need to make sure the wire is connected and the screw is tight on the wire.

EDIT:

The test for that problem is to place a jumper wire between the 5 and the 6 terminal on the R845A relay and see if the burner operates. if it does, then the wires on the L8148 are connected properly and you have a defective R845A relay. If it does not, you are going to need to get to that difficult control. (If you remove the water heater you can easily get to that control)

End Edit

There will be 2 wires under that R screw terminal. Make sure both are properly connected.

Here is a picture of the proper way to connect that wire under a screw terminal.



LOOK AT THE ATTACHED FILE BELOW

HVACNUT

I'd like to see where wires 5 and 6 in the switching relay are going also. They're going into the aquastat, but what could it possibly connect to? Can you get the cover off the aquastat and show the wiring diagram for it? Are there ZR,ZC terminals? Could it be an L8124E? 
Typically when zoning with that type of boiler controls, and using circulators instead of zone valves, there should be a switching relay for each zone. But the basement zone is connected to the aquastat, and that will control the basement circulator, and energize the burner to run to limit. I don't see how the first Floor thermostat can properly control the burner circuit as is. Unless there's another relay hiding somewhere. 

HomerJSmith

This doesn't make any sense to me. This

If I turn on the heat to zone 1 I hear the system actuate(clicks and such)and the boiler fires up and runs for about a minute and then shuts down.

That shouldn't happen, I think. The switching relay has a two pole relay, one pole operates the circulator for the first floor and one pole is a low voltage circuit that turns on the aquastat's low voltage safety circuit and igniter/gas valve module without turning on the circulator for the basement. So, I would think that terminal 5 & 6

I'd like to see where wires 5 and 6 in the switching relay are going also

is a low voltage circuit even tho the wires are #14. The aquastat controls the boiler firing and has only one thermostat controlling the aquastat. The other thermostat is controlling the switching relay which is tied into the low voltage safety circuit in the aquastat which in turn fires the boiler.

I would like to see a pic of the aquastat and the wiring dia on the side of the boiler.

heatwanted

Problem solved(fingers crossed). A shout out to user Intplm for having me look at the most obvious thing that I should have realized to do in the 1st place.

When I turned the thermostat up to call for heat in zone 1(1st floor) the boiler responded, ignited and ran for around a full minute each time. This made me just skip the step of checking the thermostat since a signal was obviously getting to the boiler.
The existing thermostat is a dumb, heat only Honeywell ct87k that is 5 years old. Since the unit was responding to the thermostat I figured it was a long shot but I followed the advice of Intplm and jumped the wires at the thermostat and the system not only responded and fired up, but it kept running normally. I just finished installing a new Honeywell ck87k that I grabbed at Lowe’s and the system is running fine.

Being such a rudimentary heat only thermostat I figured if the system responded and ran for at least a minute the comms from the Thermostat were fine.

Thank you all for your responses and help with this!

EdTheHeaterMan

I guess we will never know what is under the cover of that Aquastat Relay. Since the problem is solved and that control is too hard to reach. At least it is fixed!

heatwanted

EdTheHeaterMan - I had not posted pics since the check on the thermostat resolved it. I appreciate all the info in chasing the problem.
Here is a picture of under that cover.