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Question DetailsAsked on 8/22/2016

i had a water heater installed and now have no cold water. is this related to the install? The installer says no

New water heater installed and I haven't had cold water since. The installer says that its not the heater. Nothing has been done to the pipes in the hose at all.

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1 Answer


But you have hot water - meaning main incoming cold line shutoff valve is open ? Five likely causes I can think of, with some diagnosis clues for each:

1) because of cold water backflowing to the water heater after he shut off the cold valve on the tank when getting ready to take it out, he then shut off some other shutoff valve on the cold water line - look around for cold line valves and check if open or not. Would be an odd case because usually there is a shutoff to the water heater to shut it off for removal or if leaking, but only valve on the main cold line is the main shutoff valve which would shut off both cold and hot water. Should have no (or almost no) water at cold faucets at all in this case, and would not be hot water at the cold faucets.

2) would be a wrong installation location, but if the cold line to the hot water tank comes off the incoming water line "before" a pressure regulator or backflow preventer, they can sometimes get stuck closed when depressurized (if he shut off entire household water). Pressure regulator will usually free up if you adjust the pressure setting higher for a bit (if adjustable type). Backflow preventer sometimes tapping with a hammer (not so hard as to break it) will free it up - otherwise replacement is best bet. If this situation (case 2) is the case, you could have from zero to any amount of partial cold water, but would be cold - not warm or hot. And if this is the plumbing layout, you would have reduced cold flow (or none) but full hot flow.

3) if you mean you have hot water in cold faucets and cold or lukewarm in hot faucet, then would be connections at water heater were swapped, so it is getting cold water from a crossover connection on the hot line into the tank, with hot water out the top to the cold rather than hot line. This would be REAL odd - not just a simple swapping of connections at the top of the tank, and would have required that he changed some plumbing other than just disconnecting and reconnecting the tank (even if he reconnected it backwards, which would still normally put hot water in hot lines - just would not be the hottest water and would run to warm or cold a lot faster than normal use). Would be pretty hard to do swap anyway unless prior or new tank is foreign (some of them have hot and cold on opposite side of normal US practice), or connected with flex tubing and he crossed up the flex lines hooking them up. AND would have to have a cross-connection to provide cold water flow to the hot fitting on the tank - like a hard-plumbed connection rather than a tempering valve on a toilet. In this case you would have full hot at the cold faucets, and could be warm (same temp roughly as toilet tank inflow) or cold at the hot water faucets. Would likely also have less than normal flow rates hot and cold both. Check owner's manual as to which fitting is hot and which is cold on the water heater, then feel pipes (carefully) a couple of feet away from the top of the heater to see if hot is connected to hot or cold fitting. (Couple of feet away because right at top of tank, especially if no hot water is being used, conduction and hot water expansion heats the first few feet of the cold pipe too.

4) if you have a hot water recirculation pump and system on the water heater ("instant hot water" system) could be he hooked that up to the cold line somehow - but would have had to be really zoned out to do that because usually one would just unhook old heater and hook new tank up at same connections, so would not get involved in the recirculation system at all. However - because the recirculation systems recirculate hot water into the cold inlet of the water heater they are connected to the cold water line at that point - so if the backflow preventer on the cold line stuck OPEN, you could get mixing of hot water with the cold. If this were the case, would have hot and cold mixed in the cold pipes and full hot at the hot pipes. Or depending on how plumbed, could have hot in the cold pipes initially, but cooling down to mid-temp or only luke warm with prolonged flow.

5) Let's see - what was number 5 - oh yeah - toilet tempering valves generally have backflow preventer valves in them, to keep hot and cold water from mixing back into the household lines - the mixed water should only go to the toilets. If yours stuck open or got grit in it (which can happen when pressure is lost in the household piping), then you could have hot water crossing over into the cold line, especially when there is not a lot of hot water being used. Could be anything from slightly warm in cold lines to mid-temp like toilet tank gets. Hot lines would still be hot. In this case, if the tempering valve is accessible (may be one per toilet, or one for several if close together) feel the two pipes going into it (one comes out, commonly 1/2" rather than 3/4") - one will be hot from water heater, other should be cold, at least when toilet is refilling, If hot or warm when toilet is refilling then you are getting backflow into the cold line from it. Of course, like the water heater pipes, when just sitting there the hot water line will heat the valve and first foot or two of cold pipe to warm - that is normal.

Unfortunately, would take a bit of an investigation to tie down which of these is the problem, but the clues above might help you track it down. If you can show that he hooked the tank up so you are getting hot water in cold lines then his error and he should fix for free. Closed valve (no water in cold faucets at all) you should be able to probably find on your own and open. Other causes would not be considered his "fault" - could be because of a valve stuck because the water pressure dropped, but would be coincidental and not his "fault", so his charging to fix those causes would be reasonable.

Answered 3 years ago by LCD

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