Water Filter

[KWKloeber]

email from ShurFlo:"

...water heaters always have thermal expansion our check valve is not design to withstand the water heaters thermal expansion. The check valve will break in half I have seen it.  The old check valve with the bolts could handle more back pressure. The new one is sonic welded and can only take max 125psi max. Not good for water heaters they will develop a lot more than 125psi thermal expansion.  -- Shurflo Customer Service

The Jabsco product info says it's meant for marine and RV water heaters.


-ken

[Jon W]

Looks like Shurflo should update their documentation to say that. I'm curious now what the cracking pressure of the relief valve is. I will look when I get to the boat in the morning. Thanks for the information.

[britinusa]

Thanks for spotting the omission of the check valve. It's installed about half way between the Tank and the 'manifold'

Pic updated.

Regarding the thermal expansion pressure.

Found this on the web:

As a point of reference, in a residential hydronic heating boiler we actually observe an internal water pressure rise from 12 psi cold up to 28 psi hot as the boiler temperature increases from perhaps 60 °F up to 180 °F.

I also found a reference that water expands approximately 4% before boiling (~75ºF - 211ºF)
Tank is about 6 gallons(?) > 4% = 0.24 gallons, quite a bit but we never heat the water above 160ºF due to the engine thermostat.

and residential systems have used copper piping for years (now changing to plastic), but we use plastic/vinyl and they expand quite a bit.

So with about 12' of hose from the tank to the bathroom faucet, and a couple more to the Galley faucet, that's a lot of hose expansion.

Just sayin.



Paul

[KWKloeber]

Looks like Shurflo should update their documentation to say that. I'm curious now what the cracking pressure of the relief valve is. I will look when I get to the boat in the morning. Thanks for the information.

Jon

I measured the cracking of the current (welded, not bolted body) ShurFlow CV.  I had one in WM a few years ago and couldn't crack it by blowing a reasonable pressure.  If I went blue in the face, I could barely crack the valve.  I thought that strange and so did the WM store mngr, and we both felt they might be defective.  He gave me all in stock (no charge), as I wanted to check them against a pressure gauge.

I hooked them to a water column and discovered that about 4'-5' of water would crack them.  That's like 2 psi, which surprised the heck out of me.  Doing some research I found that "we" can typically build up only 1-2 psi over atmospheric with our diaphragm/muscles/lungs.  Of course, some behemoth could do more (like blow up a truck tire) but "normal" folks, not many PSIs at all.  So the fact that it took all I had in me to crack the CV was normal (was not defective.)

ken

[KWKloeber]

Looks like Shurflo should update their documentation to say that. I'm curious now what the cracking pressure of the relief valve is. I will look when I get to the boat in the morning. Thanks for the information.

Jon, the literature for my Seaward WH says the T&P relief valve is 150 psi max.  So it makes some sense that the ShurFlo CV may fail (if indeed the info that the 100 psi rating is correct.)

I wonder if the ShurFlo CV failures are (in part) exacerbated when used on a HOT water application?

Also strange, I can't seem to find that Jabsco CV being currently available ( except on clearance at WM.)  Not in the Xylem catalog or @ any supplier that I can find.

The rabbit hole is getting curiouser and curiouser....

ken

2/6/18 Update:

There are several "RV water system" CVs to be found (Valterra, Camco, Aqua Pro, etc.) but I can't find their P&T rating in mfgr literature.  Makes me think that they may not be good for a WH use.

The SharkBite CV is rated 200F/200 psi, so I'll stick with that. 

If one uses the 1/2" SharkBite with 1/2" copper tubing stub outs, 1/2" reinforced water hose can be warmed and forced over the tubing, and double-clamped (w/ ABA/AWAB, of course.)  That maintains essentially 1/2'" flow thru the system (opposed to reducing flow to ~3/8" with plastic 1/2" hose barbs.)  Or use 5/8" hose to the WH and cold water supply tee, (5/8" hose will slip loose, but double-clamp down ok on 1/2" hose barbs, which are slightly under 5/8" OD on the barb.)

k

[Jon W]

The metal tag on the relief valve of my water heater says it opens at 150 psi at 212 degrees. The only way it should reach 212 is with shore power, engine coolant shouldn't exceed 165. Maybe that's what the OEM thinking was. A 100 psi check valve in a potential 150 psi system is not ideal.