boiler no heat

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Old 02-10-04, 05:24 AM
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boiler no heat

hello all,
well, i have a new problem. got up this morning and heat was around 65 degs. i have a 2 zone,circulator,hot water system.

the programmable thermostat is set to 65 deg. overnite and set to come on a hour before i get up, to 70 deg.

this morning the house was 66 deg and not 70. The circulator pump was running,and the pilot flame was on. water temp was down to about 15 and boiler press was about 25.
after scratching my head,i set the other zone's manual honeywell
thermostat to 70,and the boiler came on and started heating .
i turned down the honeywell manual therostat and shut the programmable off,then on a couple of times. boiler came on and then shut off as i would expect.
I don't know if this is a fluke or what. several days i had to have the gas valve replaced because of a cycling on/off problem.
everything was fine till this morning.
Would the batteries in the programmable thermostat be the problem? The programmable thermostat its self? gas valve?
thanks,
daswede
any input would be appreciated.
 
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Old 02-10-04, 09:20 AM
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What kind of program T-stat you have? Yes. a weak battery may cause it to go funny.. Replace them..

How long you had this program T-stat?

WIll the system cycle on and off fine if you set the t-stat to "hold"?
 
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Old 02-10-04, 10:05 AM
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Id say its more in the way the boiler is wired in. You say you have two zones here and two tstats. Now the tstats should control the zones pumps or valves. Then burner in the boiler should be controled by the aquastat there so you have hot water when a zone calls for it


water temp was down to about 15 and boiler press was about 25.
The temp should be about 160o on 180o off

How many floors do you have here 1 floor set about 15 psi 2 floors 18 psi. Is expansion tank water loged?????

ED
 
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Old 02-10-04, 10:06 AM
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Hi Jay,

iv'e had the programmable thermostat for 7-8 yrs.
i must admit i don't recall replacing the batteries this year.
When i put the prog.t-stat in the "off" position and turned up
the manual honeywell. it worked o.k.,and when i switched the program t-stat the system appeared to function as normal.

i guess i thought that the batteries were just for a power failure back up to save the program memories in case of a power failer.

maybe,as you mentioned, i will change out the batteries.
 
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Old 02-10-04, 10:56 AM
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the boiler temp and pressure came up when the manual t-stat was turned up. The prog.t-stat was calling for heat this morning and the its circulator pump was running and the return line was slightly warm,however with this going on ,and low temp and press. readings i thought the burners should have kicked on when the temp/press settings dropped below a certain setting.
 
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Old 02-10-04, 11:43 AM
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It almost sounds like one of the zone valves is not wired in correctly. The zone valves end switches should both go to the terminals on the aquastat that start the pump and the burner. There is no way that a zone valve should JUST start the circulator. Can you follow the wires from the top 2 terminals on the zone valve and make sure that both valves terminals are tied in parallel? I had one yesterday with a bad end switch but that didn't start the circulator either.

Ken
 
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Old 02-10-04, 11:52 AM
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my system doesn't have zone valves. each zone has its own circulator.
 
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Old 02-10-04, 12:05 PM
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Don't know where I got that idea. It's a long thread. Then my focus would be on the relay that starts the circulator and the burner. It should start the pump and go through the high limit to start the burner. Sometimes the wrong relay gets used and relies on the boiler low limit thermostat to keep the water hot enough to heat the room and just has the thermostat start the pump. There should be a set of independent contacts on the relay to go back to the aquastat and start the burner. Check it out.

Ken
 
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Old 02-10-04, 03:55 PM
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Thanks KFIELD,
good point. I will check hi and low limit settings.
 
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Old 02-11-04, 05:33 AM
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good morning ,

checked the hi/lo aquastat settings and they were o.k.
i changed the batteries in the programmable t-stat and let the system do its thing thru rest of day,and overnight. eveything was normal this morning. Now i'm wondering if the batteries play more of a part than 'back-up' to t-stats memory in event of a power failure. any thoughts??? Maybe it just was me?
thanks
 
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Old 02-11-04, 07:19 AM
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The batteries in the tstat only make its memory work . The tstat to the boiler and all its controls there work on 24 volts. ED
 
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Old 02-11-04, 10:12 AM
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thanks Ed,

thats what i thought,but wasn't sure. best to ask the 'pros'.
i still think i have a problem. i came from work early and found the temp in the house at 67 degs. circulator was running,which i assume t-stat was calling for heat(this is the programmable t-stat). well, i looked around the boiler, and the temp. gauge was
120degs., the system is old ,so i am taking into account the gauges are not reading right. i opened the cover to the aquastat and was able to cycle a coil to get the burners to come on and off,checked the terminals for good contact.
for want of trying to troubleshoot this thing, my next choice was to raise the hi limit on the aquastat to 190degs. from 180degs.
system came on,has been running o.k., i know i said that before, room temp is up. Got brave and turned the other zone up,manual t-stat, it started,reached temp,and shut off.
i looked at the aquastat and am really confused that the aquastat has only a hi-limit setting. honeywell schem. shows different wiring for the "optional" low limit control,which my aqua-
stat doesn't seem to have
obviously, i'm grabbing for straws.
i guess i need a explanation as to why the burners don't fire up
when the water temp. hits ~120degs. sorry for going on,but i'm
trying to get a understanding of all this.
 
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Old 02-11-04, 10:49 AM
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Question

Id say look real good in the cover of the aquastat there.They all have like a adj. differential of from 5o to one of30o. A 190o is ok but I like it down to about 180o off and on at 160o This works out most of the time. If 180o heats the home why burn more fuel.
Could be the aquastat is bad here.

like Ken and I have said, think this way. Most of the time.When the tstat upstairs say they want heat. They should turn the pump on for that zone and have hot water right now the control on the boiler the aquastat should just be keeping the boiler water hot at 160o on and a 180o off or what its set for.

Ok you raised it to 190o and it came on. Did the burner go back off at 190o??????? and come backon at 130o?????????

ED
 
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Old 02-11-04, 11:46 AM
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There is only one way to start that burner and that is to close the T & T terminals on the aquastat. That is done by a pair of contacts on the circulator relay that is part of your second zone. The thermostat wires from zone 2 come into a relay that is connected to your circulator and the aquastat. The circulator part seems to be working fine but the contacts that start the burner apparently arent working. It could be due to a broken wire. You really need to focus on the wiring from the second relay to your burner if you plan on finding this problem this winter. Don't bother with the high liomit setting because it obviously works or zone 1 would not work correctly. If you tell me the model number of the relay used on zone 2, I will tell you which terminals you need to trace out. It really boils down to one wire. Stop spending time with the thermostat and aquastat and just focus on that relay.
 
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Old 02-11-04, 12:13 PM
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thanks for your reply Ed and kfield,

Honeywell aquastat relay says its a TYPE L8148J

checked all wiring and eveything wa stight bon aquastat. also,
checked wiring on NEW gas valve that was just installed. they are tight. i'm wondering now if the new gas valve is wired right,
or its the right valve? i had a cycling problem originally and had
a HVAC tech come in to fix the problem. he determined the cycling problem to be a bad gas valve. Still can't find a low temp. setting adjustment.

Maybe its time to call the HVAC tech again and have him check it out. i don't want to do someething taht will make matters worse . His service is still guranteed and this issue didn't happen till the gas valve was changed out.
whatcha think?
 
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Old 02-11-04, 12:19 PM
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If he knows boilers and their controls for sure call and get him back. ED
 
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Old 02-11-04, 12:21 PM
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The 8148 does not have a low limit. If there is no call for heat, the boiler will go stone cold. There needs to be a connection between the T terminals to energize the burner. I would like to know if one circulator is wired into the aquastat and one has a separate relay. If so, the separate relay is where you need to look. I would like to have the model of the relay that controls the circulator on the malfunctioning zone. It is apparently not starting the burner, just the pump. I hope you understand what I'm trying to describe. The problem only exists in one zone. That rules out the aquastat and the gas valve and the 24 volt transformer. If this insn't making any sense to you, perhaps you should call in a tech for assistance.
 
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Old 02-11-04, 12:48 PM
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Hi again,
its much appreciated for you Ed, and Kfield to take the time to help me. i need to 'regroup' as they say, and decide which way to go. obviously,you both know what your talking about,and i'm just
'fishing'. thanks for your patience. will get back you when i get things squared away.
 
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Old 02-13-04, 06:42 AM
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hello all,
i called the HVAC tech back to have the system checked out. He adjusted the gas valve
and checked out the boiler controls,t-stat(s),etc.
Its been two days and the system is 'cooking' along fine. i
just wanted to get back to give you aup-date.
thanks,
daswede
 
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