Boiler works for few days then it doesn't respond to thermostat?

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Old 02-15-14, 12:11 PM
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Boiler works for few days then it doesn't respond to thermostat?

Hi,

I have Hydrothern 85 natural gas boiler.
Basically the boiler works well for 2-3 days or possibly longer then all of a sudden it stops working (ie it doedn't turn on the burners). So, no heat.

Then if I kick start it by connecting a small cable to where the thermostat wire connects to to screws, the flames turn on, and then it proceeds to working fine by itself until it stops again(1 day or so or perhaps after just a few hours).

I've changed two thermostats and it didn't solve the problem. One was changed by a tech.

A tech came by a few days ago and replaced the front valve and also replaced a metal wire. It worked for a few days, but the sma esymptoms appear ?


Any suggestion as to what could be causing this ?

thanks,
Acie66
 
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Old 02-15-14, 02:21 PM
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Acie, what aquastat is installed on the boiler?

A tech came by a few days ago and replaced the front valve and also replaced a metal wire
"...front valve..." ? What's that?

"...metal wire..." ? ditto, what's that?

two thermostats
Meaning that you have at least two zones on your system? Electric zone valves?
 
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Old 02-15-14, 02:54 PM
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Ace,
By jumping the TT on the boiler you've bypassed the t-stat circuit.
Although you have changed the t-stats.and have the same problem you may have a bad t-stat wire from the stat to the the boiler or check your TT terminals for a good tight connection.
Next time it goes off, instead of jumping from he boiler jump from the t-stat itself. Remove the stat and jump the 2 wires on the wall. This will eliminate the stat. If it doesn't start you may have a bad wire you're sharing with a mouse.

Being vegans they love wire insulation.
 
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Old 02-15-14, 04:05 PM
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Unless there are zone valves involved... in which case could be bad 'endswitch'.

you may have a bad wire you're sharing with a mouse.

Being vegans they love wire insulation.
Rats are worse! They are omnivores, they'll chew right through the wire itself! I think they like the 'kick' they get when they hit the 120 HOT wire.
 
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Old 02-15-14, 05:39 PM
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Just an FYI that boiler has a power pile.........
 
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Old 02-15-14, 06:16 PM
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Just an FYI that boiler has a power pile.........
Yes, and that may be the 'metal wire' that Acie said was replaced.

Still waiting for clarification on that.

Powerpile systems are very susceptible to 'dirty and oxidized' switch contacts.
 
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Old 02-16-14, 07:59 AM
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The tech instaled:
1. a 36" universal millivolt generator
Fits 600-750 Millivolt Pilot Burners.

2. Installed the RobertShaw 250 to 750 Millivolt Combination Gas Valve
modek:7000BMVR

The tech thought the recently installed thermostat was defective and replaced it.

Let see how long this will last ?

I will update this in a wek to see if the above plus thermostat chnage does the trick.

thanks guys,
Acie66
 
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Old 02-16-14, 08:20 AM
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Please answer... because I have a feeling you will be back...

Acie, what aquastat is installed on the boiler?
two thermostats
Meaning that you have at least two zones on your system? Electric zone valves?
So when you say 'two thermostats', you mean that the same thermostat was replaced twice?

Or is the system zoned?
 
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