[RE-wrenches] Pt valves as overheat control

Tue Nov 11 13:37:38 PST 2008

My pleasure - but I also wondered if you might not have a thermal 
expansion tank in your system? Perhaps you could also try one of the 
Watts Valve commercial valves like the LL40XL. As I recall, these valves 
have another type of seat that isn't as prone to gumming up like the 
regular residential variety.

Cheers,

Matt

Roy Butler wrote:

> Matt,
>
> Good suggestion.....real hard water here. My water coil needs cleaning 
> twice each heating season....a royal PITA.
>
> In addition to the weeping, the P/T valves also start leaking around 
> the valve post too,
> so I figure I'm better off replacing it anyway.
>
> Thanks!
>
>Roy Butler
>NABCEP Certified Solar PV Installer®
>NYSERDA eligible PV & wind installer 
>Four Winds Renewable Energy, LLC
>8902 Route 46
>Arkport, NY 14807
>607-324-9747
>
>www.four-winds-energy.com
>www.nationalsolarsupply.com
>
>Although no trees were killed in the sending of this message, 
>a large number of electrons were terribly inconvenienced.
>
>  
>
>
>
> Matt Tritt wrote:
>
>> Hey Roy,
>>
>> T&P valves leak after X amount of time in direct proportion to the 
>> mineral content of your water supply. Minerals are deposited on the 
>> seat surfaces and prevent complete closure. My hunch is that 
>> installations in areas with very low mineral saturation of the water 
>> source will have much longer periods of time between 
>> leaks/seeps/dribbles and oozing. Maybe you can fix these valves by 
>> immersing them in a vinegar bath for a day or so instead of replacing 
>> them?? O course you would have to have the valve open for this to 
>> work, so maybe the vinegar would have to be boiling!
>>
>> Matt
>>
>> Roy Butler wrote:
>>
>>> Hi guys,
>>>
>>> I have been using the SS water loop in my Amish wood cookstove
>>> for my domestic hot water for 9 years now. My tank is a 40 gallon
>>> electric water heater (space saver unit) and is configured for thermo
>>> siphon operation.
>>>
>>> The P/T valve is all I have for protection and I have to be honest,
>>> I kind of knew this was probably not a great idea right from the start!
>>>
>>> But it works....the valve opens up and discharges into a piping system
>>> located under a raised bed planting area in our attached green house.
>>> So we get the benefit of the 'waste' heat. The valve opens, on average,
>>> about 1 or 2 times a week during the coldest part of the winter.
>>>
>>> I replace the P/T valve every other heating season because it does
>>> begin to weep a bit. So that may be what's saved my ignorant butt
>>> from being blown to bits.....maybe.
>>>
>>> My question....is there a more robust version of that P/T valve
>>> that I should be using? Something that you would use in a boiler 
>>> perhaps?
>>>
>>> I'm hoping to not have to change the system too much....I love the
>>> long, guilt free showers....more so because the electricity for the
>>> pump comes from my off-grid hybrid system.
>>>
>>> I'm so much better at PV and wind systems....hot water scares me!
>>>
>>>Roy Butler
>>>NABCEP Certified Solar PV Installer®
>>>NYSERDA eligible PV & wind installer 
>>>Four Winds Renewable Energy, LLC
>>>8902 Route 46
>>>Arkport, NY 14807
>>>607-324-9747
>>>
>>>www.four-winds-energy.com
>>>www.nationalsolarsupply.com
>>>
>>>Although no trees were killed in the sending of this message, 
>>>a large number of electrons were terribly inconvenienced.
>>>
>>>  
>>>
>>>
>>>
>>> Todd Cory wrote:
>>>
>>>> Sure, but the discussion was about preventing hot water storage 
>>>> tanks from exploding. Putting BTUs into a tank, whether that  be 
>>>> from a wood stove loop or 5 kW electric heating element is not the 
>>>> issue. Relying on a P/T valve to regulate overheating is of course 
>>>> not a good idea, but it will prevent the tank from exploding.
>>>>
>>>> Todd
>>>>
>>>>
>>>>
>>>> Conrad Geyser wrote:
>>>>
>>>>> Todd,
>>>>>
>>>>>  
>>>>>
>>>>> I'm afraid that any PT valves that I've ever known have continued 
>>>>> to weep indefinitely after one or two overheat triggers. 
>>>>>
>>>>> I would not recommend relying on them for heat control devices.
>>>>>
>>>>>  
>>>>>
>>>>> Conrad
>>>>>
>>>>> Cotuit Solar
>>>>>
>>>>> NABCEP thermal cert.
>>>>>
>>>>
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