Vaporstat shelf life?

Ken Johnson

My current Vaporstat (controlling a Burnham residential boiler, single-pipe steam) is now 6 years old. The predecessor failed at five years. I like to have parts on hand that are likely to need replacement soon. What is the shelf life of a Vaporstat? If purchased and stored, how will the operating life be affected?

Thanks,

Ken

EBEBRATT-Ed

Doubt that any storage time would affect it if stored under normal temp and not exposed to high humidity or moisture.

Mad Dog_2

If it's built properly, 100 years! Unfortunately, Honeywell had a bad batch a few years ago, but I haven't had any problems in last 5 yrs. Mad Dog

EdTheHeaterMan

I believe that don't really have a shelf life. There is a chamber in them that will open and close the switch contacts at that set pressure (the pressure you select). As long as the seal on the chamber is intact, it should last forever. Where your old one failed was from use over time and perhaps the chamber ended up with a pin hole leak. Is your system short cycling? like opening and closing more that 5 times per hour?

Ken Johnson

Thanks for the helpful replies.

I can't answer the short cycling question now, but I will set a reminder to check in November.

Ken

Jamie Hall

The old mercury ones will last forever — if they are never overpressured. The newer microswitch ones should last a decade in operation (the microswitch will fail), but again if never overpressured.

Even one serious overpressure event may kill them, but not always.

mattmia2

If the spare is stored in a plastic bag it will slow any deterioration of the plastics that might happen

Mad Dog_2

I hoard the old mercury T 87s, pressuretrols & Vaporstats...Mad Dog

ARobertson13

I have taken apart a number of vaporstats. I dropped them and hit them [Old and new] to see if they would fail or give bad inaccurate operation. They did become inaccurate and had to be adjusted but did not fail. They are basically well built. As previously stated, High number of cycling off and on would be the most likely cause of failure. I just remembered that a vaporstat in my building failed because the person who installed the heating controller was controlling the steam cut off by a relay trigged by pressure from a vaporstat. This meant that the vaporstat was tripping 18 to 20 times a day during the winter season.

Sylvain

It seems micro switches have a long mechanical life

see for example (page 5) : https://docs.rs-online.com/ae42/0900766b813e732f.pdf

it says "up to 10 million cycles" (but it doesn't mention a minimum).

Now I don't know if it is the same micro switch type as in a vaporstat.

Where one uses TRVs, 20 cycles a day is not much. The electrical rating might have been exceeded by the relay used.

LameyerBobonov

Extreme temperatures (either too hot or too cold) can affect the elastomers, gaskets, and other components inside the Vaporstat.