Crane Boiler - Possible aquastat problem


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Old 02-15-12, 06:28 AM
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Crane Boiler - Possible aquastat problem

Hi Guys,

I have a Crane gas-fired boiler (it's a 50's house and I think the boiler is the original one). Somewhere along the line, about 20 years ago maybe, the gas valve and aquastat were replaced.

The aquastat is a Honeywell and I think it may be going bad.

This past Monday, I woke up to no heat because the system had shut down. I cleaned the pilot (and drained the expansion tank while I was at it) and relit the pilot and got the system up and running again. Come Tuesday morning, no heat again. The pilot was still lit so I turned the on/off switch off and back on and it restarted and ran fine. This morning same story - no heat. I did the same thing - reset the power and it seemed to run fine.
So I came on here and started browsing the forum for information on my problem. Based on what I have read so far, I suspect that I may have a problematic aquastat.
As an ex-mechanic, I have worked on my system before and I am comfortable doing so.

I currently have a new 'old stock' White Rogers 948H Limit Control in my possession.
Am I correct in thinking that it is a possible replacement aquastat for my system?
If it is, is there anything that I need to be aware of when I try to install it?

Thanks.
 
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Old 02-15-12, 02:39 PM
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Hi Aramis,

What model number is the Honeywell aquastat?

Can you find a make/model on the gas valve?

I suspect that you have a 'millivolt' system and that there is a dirty contact somewhere. Millivolt systems are fairly susceptible to very slight resistances in contacts due to the very low levels they operate at.

If you can find the model number of the boiler, that might help also.

I don't think the W-R limit control will replace your HW a'stat, but get us the numbers and we'll check. Can't find anything on that control... are there any more numbers on it? How old ya think it is?

You may be able to 'fix' this problem with some contact cleaner ( De-Oxit Gold is a good one ) IF that's the problem... so don't start spraying the stuff around just yet.
 
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Old 02-16-12, 06:00 AM
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Hi NJ,

Thanks for the response, it gave me a different perspective on the problem.

The boiler is made for Crane by Bastion-Morley. Model #: 2WGA NA, Input: 165000 BTU/hr, Output: 132000BTU/hr, Working Pressure - Water: 30 lbs.

The Gas Valve is a Robertshaw-Grayson. The label faced inwards (with about 3" clearance) so I had to use a mirror to try to figure out the details. As near as I could make it, it is a 7000 8E. Other numbers on it were: 4E4-505-516 and 9204. Also: Max 1/2 PSI, 60Hz, 12VDC 0.18 Amp, 24VAC 0.2 Amp, Non regulated.

The Honeywell's label had the model number stamped in ink - it was either a L6006C, a I6006C or a 16006C - legibility was a problem. Also: .25 AMP AT .25 - 12VDC, Full load: 8.0 (120VAC), Locked Rotor: 48.0 (120VAC). Also: R-B opens, R-W closes on temp. increase.

The White-Rodgers also had the following information - Type: 1127-2, Style: 830, also: 37-1918.

I hope that this is of help to you.

By the way, where can I get that De-Oxit Gold?

Thanks.
 
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Old 02-16-12, 02:32 PM
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I wasn't able to find a ton of info on your gas valve, but I do not believe that it's a millivolt valve... from what I can tell, it is a standard 24VAC valve.

You probably won't have any luck with the contact cleaner (available at Radio Shack probably) because the 'switch' inside the L6006C HW a'stat is enclosed.

You may be able to use the W-R control to replace the 6006C. They are both 'strap on surface mount' types.

Here's the datasheet on the W-R
http://s3.pexsupply.com/manuals/1284..._PROD_FILE.pdf

Here's the sheet for the 6006C

http://customer.honeywell.com/techli...0s/60-2104.pdf

Where on the boiler is the 6006 mounted? On a pipe?

I'm guessing that the HW 6006 has wires on the R and B terminals?

I believe that there must be more controls on the boiler though... what runs the circulator? Have you looked behind any covers on the boiler? I can't find anything on your old unit... maybe it's time for some pictures...

Do you own and know how to use a multimeter?

If you can take some IN FOCUS, WELL LIGHTED, LARGE ENOUGH TO SEE DETAILS photos of all the controls you can find, upload them to a FREE account at Image hosting, free photo sharing & video sharing at Photobucket and come back here to proved a link to your PUBLIC album. Make sure to stand back and take a few wide angle shots in addition to any close shots so we can relate...
 
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Old 02-17-12, 06:10 AM
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Thanks for the links ... they were very instructive.
I have a very tight schedule at work right now so I won't be able to do any pics until Saturday.
To update you on what's been happening: When I got back home on Wednesday evening, The system was off but the temperature reading on the thermostat was within 1 degree of its setting so I assumed it had shut down normally. I decided to 'play' with it so I upped the setting by 3 degrees (which would normally make it kick on) but no luck. So I went down to the boiler and turned the power off and back on and that got it running. On Thursday evening it was not running when I got home - and the temperature was 5 degrees cooler than it should have been. So I 'played' with it - this time I turned the thermostat off and back on and to my surprise that made the system kick on. And the same thing happened this Friday morning - turning the thermostat off and back on made the system kick on.
So ... am I maybe dealing with a defective thermostat? It's a basic Honeywell digital.

As far as your other questions go -
The 6006 is surface mounted on the 3" hot water pipe coming out the rear of the boiler.
The Circulator kicks on and stays on when the thermostat is active. The boiler however cycles on and off with an upper limit of about 180.
There is a temperature gauge and a pressure gauge on the top of the boiler.
I'll check on the wiring of the 6006 when I get home.
I will also be checking and cleaning all of the wire connections - which is what I should have done long before this.
Yes, I do have a multimeter but I'm very aware of the warning label on my gas valve about possibly shorting out and damaging it or the thermostat.
 
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Old 02-17-12, 02:30 PM
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am I maybe dealing with a defective thermostat?
It's possible, but not that likely. Did you say you've changed the batteries in it?

This is just one zone, right? Only one thermostat?

Can you find the wires coming to the boiler from the thermostat? Follow them to see where they go. I'm betting that there's a 'relay box' somewhere, and it's possible that the relay in that box is what's giving you trouble...

So hunt all around and let's try to get the big picture of what we're dealing with and we'll go from there.
 
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Old 02-19-12, 06:52 AM
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So I tracked the relay down - it's a Honeywell RA89A and it looks like it may be the original one.
Currently I still need to hit the thermostat on/off switch to activate it.
What is the testing procedure for it - if there is one?

And yes, it's just one zone, one thermostat and I did change the battery for it.
 
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Old 02-19-12, 07:37 AM
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You will find the thermostat wired to the T T terminals in the RA89A, and the 120VAC to the pump wired to terminals 2 and 4.

This is what's running the pump when the thermostat calls for heat, but there's still no indication of what's triggering the boiler to fire.

There still has to be more... follow the wiring, try to find some connection between the thermostat and the boiler. There has to be something that's telling the boiler to fire.

Follow the wires coming from 2 and 4 in the 89... are they going ONLY to the pump?

Here's the data on your RA89A:

http://customer.honeywell.com/techli...0s/69-2041.pdf
 
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Old 02-19-12, 03:04 PM
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I have attached a link to a few pics of the setup:
Pictures by aramis7350 - Photobucket

The main switch feeds a junction box that in turn feeds the circulator relay by way of a 3-way BX cable. The transformer that powers the gas valve is bolted onto the cover of said junction box.
When the thermostat is engaged, the circulator kicks on and power is also fed to the gas valve transformer. Looks like 1 and 3 are unused, and 2 and 4 feed both the circulator and the gas valve transformer.
 
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Old 02-19-12, 03:28 PM
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Now we're getting somewhere! That's kinda the way I thought it would have to be.

Looks like 1 and 3 are unused
Look closer... there is a 120VAC HOT (black) wire on terminal 1. and of course that jumper over to 3 feeds that 120 to the relay to turn on the circulator, and to power the transformer for the valve.

When the system 'misses', do BOTH the circulator AND the burner not operate? If so, then the problem is most likely with the RA89A since that is COMMON to both.

If ONLY the burner doesn't fire, and the circulator ALWAYS runs on a heat call, then it's fairly certain that the 89 is OK.

Next, the BLACK wire coming off terminal 4 in the 89 is the HOT wire feeding the primary of the 24VAC transformer. Check inside the j-box that there isn't a loose connection there.

On the transformer secondary, when the system misses, check the terminals with the red and white wires for 24VAC. If there is a heat call, you should ALWAYS have 24VAC there.

Follow the red and white wires. I believe that you will find one going to one of the terminals on the L6006C. The other will go all the way through to the gas valve. The other terminal on the 6006 will go to the gas valve.

Modern boilers will have some safety switches wired in series with the voltage to the gas valve. I doubt that yours does. These would be a 'blocked vent switch', which is usually mounted on the atmospheric vent hood on the flue. If the vent were blocked, this switch would overheat and shut down the valve. The other would be a 'flame rollout switch' which would be mounted down by the burners and would detect flames rolling out of the combustion area, due to blockage in the heat exchanger. Like I said, I doubt you have either of these, but it is something to watch for.

If you always have 24VAC at the transformer when there is a heat call, you need to trace forward and determine where you are losing the voltage.

Once you find where the voltage is lost, the rest is easy.
 
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Old 02-19-12, 03:36 PM
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If you do find that the circulator does NOT run when the system misses, then the 89 as mentioned is probably the culprit. You should be able to see the contacts on that relay. Get a bright light and examine them closely. Are they all pitted? If so, replace the relay. Is there a dead spider in between the contacts? or are they really badly oxidized? If so, try the DeOxit on the contacts.

If you do need to replace that relay, there are other more modern ones that would do the trick.
 
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Old 02-19-12, 06:29 PM
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Okay!!! I think I finally figured it out ... with a lot of help from you.

As you had pointed out, when the system was 'missing', neither the circulator nor the boiler was running. I had kinda narrowed it down to the 89 because I got the circulator running one time by tapping on the relay itself. I turned the power off and pulled that apart and found that the screws holding the contact plate to the bakelite seat assembly had worked loose, causing the plate to wobble around and not make a good contact. So I took that all apart and reassembled it to the way it should be. Once I reinstalled it, and threw the switch, it fired up right away. Speaking as an ex-mechanic, I think that was the basic problem. I did go ahead and order a replacement circulator relay since I figured that after 50+ years of useful life, I was pushing my luck expecting a lot more out of it.
 
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Old 02-19-12, 06:42 PM
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Great! I knew you could do it!

figured that after 50+ years of useful life, I was pushing my luck expecting a lot more out of it.
Hmmm... you been talking to my wife? She says the same thing about me!
 
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Old 02-20-12, 07:21 AM
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Thanks again, NJ, I couldn't have done it without your help. By focussing on the aquastat, I was heading totally in the wrong direction and would probably have ended up with a $500+ bill by replacing stuff that wasn't defective anyway. Right now it's working exactly the way it is supposed to be working.
The next time I'm on that NJ Turnpike on my way to New York, I'll be the one tipping his hat to you!
p.s. I'm 60+ and my wife keeps trying to tell me it's time to quit doing this and farm it out ... so you hang in there!
 
 

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