[RE-wrenches] Pt valves as overheat control

[Matt Tritt]

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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