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cgk
Recirculating Line Issues

I have a hair pulling problem. My house is 18 months old, it is a two story with two bathrooms on the second floor. I have a recirculating line and pump in the basement, hooked up to a 50 gal. gas water heater. The recirculating line ties in to the main hot water line in the basement, just after all the first floor lines branch off. The recirc line then goes to the pump then into the bottom of the water heater. Here is the problem: with the recirculating pump and line working we will have good second story water pressure and fast hot water BUT we run out of hot water...barely enough for one shower. With the recirc. pump unplugged and the two valves (one on either side of the recirc. pump) closed we have a seemingly unlimited supply of hot water, it takes longer to get the hot water (as expected) BUT the hot water pressure at the two tubs drops considerably. So neither situation is ideal. Could the recirc pump be bad? This system did work about 8 months ago, we were slow in recognizing the problem but there was nothing obvious that happened prior to us realizing we were running out of hot water. I appreciate any feedback. Thanks.

JLMCDANIEL
Re: Recirculating Line Issues

I wonder if the pump is connected backward, so it is pumping water out of the bottom of the tank instead of out of the top. That would pick up the cold refill water. If it is a capacitive start motor and the capacitor is bad the motor may be running in the wrong direction.
Jack

cgk
Re: Recirculating Line Issues

Could something happen to cause that? That would make sense, but it did work properly at one point.

Blue RidgeParkway
Re: Recirculating Line Issues

What is the type of water heating? A free standing tank style self-contained gas fired water heater? or a 50 gal tank getting its very hot water via a coil off of a gas-fired boiler? Do you have a tempering valve between the Hot water tank and the bathroom tubs/showers? Are you using this strictly for your domestic hot water or are you also using the same system for hydronic heating for example.

Do you have water-saving shower heads? Did you remove the water saving restrictors? Have you "clocked" your shower heads (the old bucket and stopwatch method)? How long are these "showers" that you take when you run out of hot water? (calculate usage using gallons per minute from your bucket and stopwatch test times length of shower, plus calculate the water required for the path of the entire DHW plumbing loop (Domestic Hot Water supply and recirculating system).

Are your hot water lines and the return (except for the last few feet to the recirculator pump) recirculating lines insulated? Are you experiencing extreme cold temperatures where you are now? Do any of the water lines run in un-heated spaces? How is the temperature of your domestic cold water? any warm slugs?

Dip tube broken? wrong type of recicurlator system, clogged up, or perhaps you have anti-scald at your tubs. Are you actually running out of hot water (checked at other taps) and it is icy cold, or just warmer? Have you checked temperature nearest the water heater tank, how about at its drain spigot?

Do you have water quality "issues"? If you do have a gas-fired water heater - have you flushed it for sediment?

The web site http://www.waterheaterrescue.com may prove helpful as you work to diagnose the problem.

Simplest might be a failure to have a check valve between the recirculator and the tank, or one that if you do have one, it may be failing. As you create a high demand for DHW using the shower for a length of time, perhaps your system is drawing off that cold water being directed to the bottom of the tank.

Check the site I mentioned and linked to above, first look at the lingo section, and read sections for swing check valve, spring check valve, and recirculator pumps. You'd have to know if you have a water lubricating pump or an oil lubricated one (may need or be past time for servicing/maintenance). Also check for an in-line recirculator thermostat and its settings (rare in DHW systems but possible).

Plenty of other areas to look into as well, including crossover - which from how you describe your system, i'd target the first floor plumbing for that as well..

JLMCDANIEL
Re: Recirculating Line Issues

If the motor is a capacitive start motor and the capacitor goes bad, when the pump is shut off due to power failure, unplugging, etc when it is turned back on it may start running in either direction. The pump being installed backward, may have caused the problem before but may just have not been noticed. There should be a flow indicator (usually an arrow) on the pump. The fact that you have sufficient hot water without the pump is a pretty good indicator that the water heater is of sufficient size and working correctly.
Jack

cgk
Re: Recirculating Line Issues

The arrow on the pump does show the flow going into the bottom of the water heater. I can not see (at least it is not obvious to me) any check valves that would prevent water flow from the bottom of the water heater into the recirc line, I have looked all the way along the line. Is there any definitive way to check to see if the pump has malfunctioned and is pumping the wrong direction?

As John stated, I have ruled out any malfunction on the water heater itself. There is lots of hot water when the recirc. is bypassed--just no water pressure.

Thank-you all for sticking with me on this.

JLMCDANIEL
Re: Recirculating Line Issues

Make sure the pump is one and turn on the hot water in the bathroom. Feel the line between the pump and the WH. If it starts getting cold it is pumping out of the bottom of the tank.
Jack

JLMCDANIEL
Re: Recirculating Line Issues

If you one hand on the pipe close to the WH and the other on the pipe away from the WH you should be able to tell direction of flow as the pipe cools.
Jack

cgk
Re: Recirculating Line Issues

I could not tell which direction it was flowing, the temp change was too gradual to tell if it was coming from or going to the water heater. I am going to see about replacing the pump, even though I can't confirm it your thoughts about pulling water from the tank makes the most sense to me.

Re: Recirculating Line Issues

You might just setup the pump to shutoff when the second floor calls for water.

Re: Recirculating Line Issues

Does your 50 gal GFHWH look like this?

If so, how is the pump tied into the bottom?

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