The natural gas hot water tank that supplies in-slab heat and domestic water to a rental suite in my house is making a knocking noise. I’ve read that I should drain and flush it. Problem is, where I would normally drain it, is where the cold water return loops into the tank. Has anyone seen that set up before? I’m used to seeing a cold return loop into the top of a tank, not the bottom.
The tank next to it supplies domestic water to my house, but doesn’t have a cold return loop. That one i can drain.
Thanks for your help.
Shannyo
Replies
Whoever installed the system should have placed a drain valve on a tee where the return line connects.
Sorry for the delay. I've been away.
Attached is a photo. There is a drain, but it seems to me that if I open it, the water from the cold return will run, rather than the water from the tank. Or am I not understanding how this workds? I've drained other tanks before, but this one has me worried.
To drain the tank you will have to shut off the ball valve and undo the union between the valve and the tank. After that, shut off the water to the house drain the supply line to the water heater and change the existing fitting around so the drain valve is below the supply shut off, looks like you could re-use most of the fittings that you have. Sorry about that you will need a new union and a new ball valve, both threaded.
Edited 5/10/2007 5:01 pm ET by exfitter
Well, with this setup you can't drain the heater without draining the recirc system at the same time, and even then you're not going to drain the tank completely until you crack the union. Hard to get the crud out in this setup.But the arrangement is poor. Probably best would to attach the tee with one "opposite" end to the heater (via union), the other "opposite" end to the drain valve, and the odd leg going up to the recirc return line. Place the ball valve in the recirc line so you can drain/flush WH without draining recirc system.(Problem with placing the tee vertically with recirc above and drain valve below is that the drain valve leg will fill with crud.)
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