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Questions about check valves and deep sockets

Charles_8 Member Posts: 74
Today I finally hooked up the 40 gal. water heater as a storage for for my previously tankless coil. The heating elements are not powered. As recommended here, I'm using a Taco 006 circulator and an SR501 single-zone relay. The relay is controlled by the water-heater thermostats, and the boiler aquastat is the 180 degree high-limit only. When there is no call for hot water, the boiler won't run unless the thermostat calls for heat. This should save some fuel, not keeping the boiler simmering at 180 all summer, and the tank (currently set at 125) is well insulated so that also should cut the heat losses. It is working perfectly - only took a few minutes to heat the 40 gal and for the first time in three years I didn't have to play with the shower or sink faucets to get constant temperature!

But when the circulator pump is running, forcing coil-heated water into the bottom tank port, there is some backflow into the cold water input (that CPVC pipe feels warm but not hot all the way back to the tee where the cold water is supplied, about five feet). It isn't warm when the pump is off. So it looks like I need to put a check valve in the cold water line. There are several different models (and a large price range). Would the inexpensive bronze "swing" check valve work? Or the pricier Watts No. 7?


The second problem is that there is a little seeping at the bottom of the tank, just enough to be annoying, and of course it's the one connection I can't repair easily. It's the pipe-threaded fitting at the bottom of the tank that I screwed into the (3/4" NPT) hole where the cheap plastic drain valve used to be. I don't think I tightened it enough, although I did use pipe dope -it's recessed into the jacket and was hard to get a grip on.

So the question is, does anyone know of a special (1" hex) deep socket that can tighten a fitting with a 1/2" copper tube sticking out of it? Since I'll have to drain the tank anyway, the simplest fix would be to cut the tubing, tighten the fitting, and solder in a coupling. If not, I guess installing a 3/4" pipe nipple long enough to get a monkey wrench on is the next best thing...


Of course I may just call a plumber, especially since the bottom of the tank is lower than my basement sink and there's no floor drain in the basement, so a pump would make draining the tank much simpler. Sigh...


  • radioconnection_2
    radioconnection_2 Member Posts: 70

    Use a union instead of a coupling if you go through all of that work. Adding a Tee with a drain spigot might be another good idea. It will make the "next time" alot easier and let you flush the tank every year for maintenace.

    I'm curious about one thing: Why didn't you use the cold water inlet on top and cut back the length of the dip tube a bit instead of using the drain port? (I don't know which is best, just asking to learn.)
  • hr
    hr Member Posts: 6,106
    a small amount

    of thermal migration back the cold feed may not be a big issue? It's not uncommon to see some temperature back up the cold feed. Does it appear when you run a cold faucet somewhere, or is it bothersome?

    Most plumbing suppliers have heat trapper nipples for HW tanks. It may be easier then a check valve install.

    If you do add a check valve you will need to add a thermal expansion tank rated and sized for DHW use. If not the check will cause the pressure to increase in the tank and possibly pop the pressure relief valve, as it will have no where to expand to with the check valve installed.

    Plenty of deep sockets available to buy or borrow :) Inexpensive thin metal faucet repair sockets can be purchased at plumbing supply stores. Also get a compression coupling, or a SharkGrip fitting to make the repair without soldering.

    You might consider removing and using teflon tape and pipe dope.

    Or build another short nipple and do the change out "on the fly" by allowing a vacumn in the tank to hold the water in. A common approch to replacing electric tank elements for the boldest of plumbers.

    hot rod

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  • Charles_8
    Charles_8 Member Posts: 74
    More info...

    Thanks for the tips, everyone. The Sharkbite fittings sound like a great idea - that way I don't have to drain all the water in order to solder!

    It is hard to see in the pic, but tucked up in the joists is a 5 gallon expansion tank. The previous "plumber" didn't have ANY kind of expansion tank installed on the coil, so naturally the pressure relief valve was prone to weeping. I did my homework before spending money or cutting any pipes :)

    Also I did install a tee on the bottom line, with a drain valve on it. Not sure it shows in the first pic (it's closer to the boiler end of the tube along the bottom). There is a separate shutoff valve for the lines coming to/from the coil, so I can drain just the tank by closing the coil valve and opening the teed drain valve.

    The backflow really isn't much of a problem I guess, (I don't feel it in the cold faucets), but I want to maximize the efficiency of this arrangement., I

    The reason for using the drain port, not the cold port, is that there has to be somewhere to get cold water into the tank :) Cold water comes into the tank through the cold port, out through the hot port to the house as usual. I added a tee on the hot line which goes to the circulator pump, which pumps through the coil and then back to the tank). I figured the tank would heat more evenly if I put the coil-heated water into the bottom and let it rise. The other reason would be if I wanted to convert to straight electric water heating. Then it would be simple just to remove the pump and coil plumbing and cap off the hot-side tee.

    I have changed things like coolant temp switches on cars/trucks without draining the radiator, just work really fast! I suppose that would work with a 40 gal. tank of water, and not be TOO messy ;) With the water shut off, there is only at most 2 psi trying to force water out (from the four feet of head).

  • Charles_8
    Charles_8 Member Posts: 74

  • Charles_8
    Charles_8 Member Posts: 74
    I may have misdiagnosed this drip... Condensation?

    I may have overreacted, or misdiagnosed the problem, or most likely both ;)

    This morning I looked at the bottom of the tank again and the 2x4 is almost completely dry. There is still a little bit of moisture but nowhere near as much as on the day of installation. With all faucets closed, the water meter dial (.001 CF per division, about 1 ounce) does not move at all.

    When I had first filled the system with 40+ gal. of cold water, I noticed that the water-filled portion of the expansion tank immediately began to sweat profusely. My basement is humid in summer due to water leaking in along one wall and early July was quite rainy in northern Maine. The first six feet of line from the street and the meter constantly sweat.

    Anyway, it has belatedly occurred to me that the entire steel water tank would have also sweated immediately, and in even larger amounts, and that condensation would trickle down along the tank all the way to the bottom of the heater! The expansion tank surface has now stopped sweating too.

    Keeping my fingers crossed :)

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