This is a followup to a prior question. We had our hot water heater replaced. The guy who did it recommended removing the small overflow tank, since we are on well water with a pressure diaphragm, and added a bronze check valve of some type on cold water line. We also have a water recirculation system with an electric pump a foot away from the hot water heater. This pump reconnects to the cold water line between the check valve and the water heater. The first time I tried to take a shower after they were here I could only get tepid water. I turned off the flow to the recirculation system, and now I got real hot water, although I have to wait about three minutes for the hot water to start. As part of figuring out what was wrong I got the hot water running, turned the recirculation system back on, water temp. from the tap dropped to tepid. I left the water running, turned the recirc. off, and presto, hot water again. Felling the pipes, the copper line connected to the recirculation system remained cold. Somehow, it seems that water is flowing the wrong way through the recirc. system. Clearly, the installers will have to come back and fix it. Does anyone recognize what they did wrong? I would like to be prepared in case they try to snow me. Clearly they did something wrong, everything worked fine until they showed up.
I was going to say something to the effect of “hot water doesn’t need heating”, but thought better of it.
Shouldn’t the pump connect to the return water line Before the check valve… not after? Plus it seems the pump is mounted with the flow in the wrong direction.
When the pump is on it’s pulling tepid water from the bottom of heater. When the pump is off; it and the check valve prevent tepid water from flowing from the bottom of the heater and all the water is flowing from the the top of the tank where the water is hot.
This is just a wag. I don’t really know anything about this stuff, but maybe someone will come along and explain it correctly.
I’m going to guess that the pump is installed backwards - or maybe sideways, it’s hard to say from your description of the system.
There are two ways to install it in your situation, with the pump at the water heater. One is for the pump to be installed in the hot water line where it takes it suction from the water heater and discharges to the house. The other method accomplishes the same thing, but the pump is installed in the cold water line taking suction from the cold water supply and discharging to the water heater. In both installations there needs to be a return or crossover valve at the farthest fixture from the water heater.
Here’s how it works; The pump circulates hot water through the hot water lines at all times, using your cold water lines to close the loop and bring the water back to the tank to be reheated and recirculated. The upside is instantly available hot water throughout the house. The downside is higher energy bills due to heat loss in your (likely) uninsulated water lines and the cold water is not very cold due to mixing with the circulating hot water.
If the pump is installed backwards, it will severely decrease hot water flow while running and it will probably severely shorten the pump motor’s life. Even when not operating, the pump will act as a restriction to the hot water flow.
Carefully inspect your pump to see if it has a flow direction marked on it. If it is installed on the cold water line between the cold water supply and the tank, the flow direction should be toward the tank. If on the hot water line, flow should be away from the tank.
Well, the thing is that the pump was working just fine for ten years, then the tank began to leak, was replaced, and now I have the problem described. It has to have been something they did. I wonder if the return line should be above the cold water valve, rather than between it and the hot water tank, although I can’t think why that would matter. I was thinking maybe they let the pump run without water and burned it up but it doesn’t seem likely that would cause the strange circulation problem of mixing hot and cold water unless I shut off flow through the line that returns water to the cold water end of the recirculation system.
This is a shot in the dark, but could they have rewired the pump motor, so that it’s turning backwards?
Well, they shouldn’t have touched the wireing. I don’t know, but it seems like something more than that seeing as how the hot line “steals” water from the cold line for me to end up with tepid water at best with the recirculation line open.
Yeah, my suggestion was kind of lame anyway. I’m having trouble picturing the hookup, but if they just replaced t W/H and installed a check valve, I don’t see how the system could have been changed.
On a hot water recirc. sys. they usually run a H/W return line from the furthest point back, of the H/W line, to the W/H and install a small pump to pull water back to the tank. As someone else mentioned, you should make sure that all your H/W piping is well insulated, or you will be paying much higher energy bills.
To help me picture your system, please describe the piping connections to the pump a little more thoroughly. Specifically, where does the pump take suction and where does it discharge. Check the pump for flow direction and include that information as well. I’m pretty sure the pump was mis-installed, but I’m having trouble picturing your setup.
Instead of a dedicated once-hot-now-cooled water return line as someone mentioned, some systems have a thermostatically controlled valve at the far end of the plumbing string. The thermostatic crossover valve connects the hot & cold feed under a sink.
I have a system like that & it works great.
The pump is inline in the hot water output from the heater tank. When the pump runs, it slightly pressurizes the hot vice cold feed to the rest of the house. The thermostat crossover valve at the far end will sense the temp in the hot feed.
When the hot water feed is actually hot, the crossover valve is closed & the entire system operates normally as if the recirc/crossover wasn’t installed.
When the hot feed water cools enough the valve crossover opens allowing pressurized now-cool ex-hot water to flow backwards into the cold feed. As fresh recently heated still-hot water gets there, the valve closes again. The result is the hot water feed is always warm-to-hot and the cold water feed is often tepid, only occasionally cold.
For faucets other than the one with the crossover, you get normal cold side behavior and also much quicker to near instant hot side behavior.
By insulating most of the hot water feed pipes, we’ve seen this system cost almost nothing to use while being extremely convenient in a large house with 100’ pipe runs from heater to faucet.
In the OPs case, I’d wonder if somehow they got some gunk in the lines which has clogged up whereever your return thermo-valve is.
As well, if there is any crossover plumbing between the hot & cold side near the pump & heater, I’ve got to wonder if they didn’t misunderstand what you had and reconnect something totally bass-ackwards.
Are you really sure the plumbing is now routed exactly as before, or are you going from guesswork?
My installation has a valved bypass around the pump & if somebody working on it had no clue what it was & attached the bypass to the heater’s cold-side inlet they’d produce the symptoms you describe.