Burnham boiler problem with Taco 595 thermostatic bypass valve


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Old 12-31-09, 01:56 PM
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Burnham boiler problem with Taco 595 thermostatic bypass valve

I'm out of ideas. I have a Burnham PXG-2004 boiler with a 4 zone system. The problem is that the boiler gets to the limit temp but does not supply any hot water if the limit is set to anything other than max ~220.

I have checked and confirmed the limit switch setting, the boiler pressure is ~15psi when cold and 23 when hot @210. I've checked the circ pump and have purged the system with no help.

I think this Taco thermostatic bypass valve is bad. It is supposed to caused circulating flow around (bypassing) the boiler when below a certain temp (~150 i think) and cause all circ flow to be through boiler when boiler temp it hot (180)

I can't find a replacement for this valve anywhere. I've been told this valve is not even necessary and I should just plumb around it. I'm skeptical.

Any ideas or suggestions will be greatly appreciated.
 
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Old 12-31-09, 02:51 PM
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Can you show us some pics?

Free account, Image hosting, free photo sharing & video sharing at Photobucket , upload pics there, drop a link here to your album.
 
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Old 12-31-09, 03:08 PM
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Is this what your valve looks like?

5000 series mixing valves
 
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Old 12-31-09, 03:20 PM
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Maybe this will help?

A. Contact Parts to Your Door (866-723-5299 or www.partstoyourdoor.com). Taco does not make the 595-1 Bypass Valve or the bypass element anymore, but Parts to Your Door has the Bypass Valve in stock. It is stock code 51807. The bypass valve or the bypass element can be replaced.
I guess I should have checked the link first... doesn't seem any good?

Google does have a snapshot of their website from a couple days ago... so I'm guessing it might just be a temporary glitch on their site... maybe give them a call?

Happy New Year!
 

Last edited by NJT; 12-31-09 at 03:42 PM.
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Old 12-31-09, 04:25 PM
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Thanks. I saw that link and cache of the partstoyourdoor page and like you, found the link broken. The picture you sent is not the correct valve, but i think it's operation is similar. I could not find the phone number for them so that will help. I had a hvac contractor friend of mine search high and low and everyone was unsuccessful at finding that valve.

The main problem with all the cross ref versions is that they do not allow for the mounting of the high limit set switch. The 595 casting has an internal well for the switch. I ended up machining a plunger that replaces the plug/bleed cap originally installed on the top of the 595 valve that I adjusted to just the correct length to push the valve off the seat inside.

I now at least have heat. The only problem, of course, is that the valve does not close when the boiler temp is cool and therefore allows cold water to enter the return line of the boiler which I believe could eventually cause problems with condensation. I should be OK for a while like this, but really like to find a replacement.

I'll try that number and see if they can supply.

Thanks for the help!
 
 

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