Weil-McLain indirect water heater safety valve

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  #1  
Old 03-22-04, 10:07 AM
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Weil-McLain indirect water heater safety valve

We have a Weil-McLain indirect water heater which takes the hot water from our boiler at 180 degrees and circulates it around a tank with the domestic hot water in order to heat it.
The thermostat of the domestic hot water is set at 130 degrees. The unit is about 3 years old.
On Saturday, I installed a Laing Autocirc pump in our master bath. It basically pumps water from the hot water line under our sink in the master bath through the cold water line back to the water heater when the temp of the hot water is less than 85 deg and then shuts off at 95 deg.
Then, when you turn the hot water on in the sink, it is pretty much instantly warm.
It seems to work well, but when I went down in the basement this morning, I noticed that about 6 feet of the floor around the Weil-McLain was damp (the safety valve on the top had released some hot water during the night).
What would cause that to occur? The technical person from Autocirc said it would not be his product because it only pumps with a very low pressure. (he said it only adds 1 psi to the pressure in the line). We also have a booster pump in our main water line since our city water pressure was very low. It turns on at 50/off at 70 in order to run our sprinklers.
Up until today, we have never had a problem with this setup.

The website for the Autocirc is:

www.autocirc.com

Thanks.
Dave
 
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Old 03-22-04, 05:38 PM
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The T&P valve only releases water for 1 of 2 reasons.
Temperature or pressure.

I'm kinda curious about your pumping arrangment. Are there any check valves on the water system booster pump?

I'd be looking at the pressure angle with elevated pressure from heating more water than the system normally held. A little expansion goes a real long ways on pressure. You are making a heated return line back to the water heater and even this little bit of heated water has expanded some.

Now to check this, buy a pressure gauge with a lazy hand which you can place on any convienent faucet and let it set there overnite while everything is off.

Hope this helps, any questions or problems, ask and someone will answer you...
 
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Old 03-22-04, 05:52 PM
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There is one check valve in the pump in that when the pump is pumping water from the hot water line into the cold water line, the check valve is open.
As soon as you open the cold water faucet, the check valve closes so only water from the cold water line comes out the faucet.
I had the pump running on demand all day yesterday. I put it today on a timer system where it comes on between 5-8 Am and 8-11 PM since these are the hours we mostly use it and so far no more problems.
I spoke with the Autocirc people again and they said there is no way their pump could be doing this. I'm not certain about that.
 
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Old 03-24-04, 10:25 AM
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Hello: Dave4242

Suggestion. Recheck the piping. Circulating pumps commonly do not recirculate the back into the cold water line. They circulate the returning water back into the water heater, usually at the flush spigot or flush faucet.

Some call the tank or boilers flush valve a spiget valve or faucet valve. (Flush and drain faucet/spigot vlave. Same valve different terms.

A recirulation pump is usually located at the water heater and not under the sink or in the cabinet. At the heater, at least on tank type units. Boilers may differ as well as the type of recirculation pumps.

Whole house pumps are located common at the hot water unit. There are some small pumps which can be installed under a cabinet for a specific sink, tub or shower.

I am not familar with such undercounter units. Is the one you have for undercounter installation or at the heater type?

Of course the manufacturer claims it is not their fault. Denial is always the first line of defense...LOL!......excuses come next once the problem is found to be there fault......
 
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Old 03-24-04, 01:37 PM
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No, The recirc pump definitely goes under the vanity and takes water from the hot water pipe and recirculates it through the cold water pipe.
It is a new system called Autocirc made by Laing. The website is: www.autocirc.com
I spoke with the people from Weil-Mclain, and it appearss that we have the wrong T&P vlave on the indirect water heater.
We have a Watts 100-XL-3, and it should be a 40-XL-8.
I'd assume I must just turn off the water supply and decrease the pressure in the heater to replace this valve.
In the installation manual, it talks about filling the inner tank with potable water before filling the outer tank with the boiler water. Does this mean I must also drain the boiler water before decreasing the hot water preesure in order to replace the T&P valve?
 
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Old 03-24-04, 03:57 PM
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Yes it does.

Turn boiler off also.

Did you happen to check to see if there was a check valve on your whole house pressure pump? I would be interested about this.

These little auto-recircs use the cold water lines as the retrun to the water heater. Neat idea as it replaces a long run of pipe usually dedicated for this purpose. Thought process is you will use less cold water for cold water than "cold" hot water while waiting for hot water.
Problem is, this cold line also heats up and adds a little water expansion (which means pressure) to the system.

Let us know how the new T&P valve works for you...
 
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Old 03-24-04, 04:10 PM
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There is what appears to be a check valve where my water main enters the booster pump. Then the water goes from the pump into a large pressurized holding tank (with an air bladder) before going out to the different parts of the house.
Wouldn't the holding tank act as an expansion tank too?
The T&P valve currently on the indirect water heater is rated to 100,000btu whereas the one that is specifed is rated to 200,000 btu. I will replace it tomorrow, but if this doesn't fix the problem, I will probably return the autocirc unit.
 
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Old 03-24-04, 05:41 PM
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Yes it should unless there is a hole in the diaphram or just no air charge. Then it just a tank of water. Throw some air it and see what happens after you change out the T&P valve.

The current T&P is a big no no. The valve IS ALWAYS oversized so if there is any problem, the valve can vent more than the heater can produce. There will be the BTU rating for the unit on the unit label, make absolutely sure the T&P valve has a higher rating.(there will be a metal tag with the BTU rating or AGA rating for the valve, attached to the valve) You have saved yourself and family in ways you do not want to know. I'm being serious about this, this is a biggie for safety devices.
 
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Old 03-24-04, 06:40 PM
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Thanks for the advice. I will be changing the valve tomorrow to the correct one.
Now, the current setup has the T&P valve sitting in a tee which is about 3" above the top of the indirect water heater. The current T&P valve has a 3" thermostatic sensing bulb.
The one that is specified has an 8" sensing bulb so it will be in the water in the tank.
Should my current setup be OK (with the tee in place)? In other words, the bulb will protrude 5" down below the tee (which is definitely down inside the heater).
I just dont understand how much of the bulb should be inside the heater (the present one must be only in the tee).
 
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Old 03-24-04, 07:51 PM
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Over half will do as long as it is in a location that water is able to move freely around the sensing bulb with water that is representive to the true nature of the heater.
Just stuck in a tee with the side port plugged would not work as the water would be stagnant. The side port of the tee has to have water flowing through it with water going somewhere within the system.
Boiler code as well as plumbing code requires the T&P valve (Safety Relief Valve on boilers) to be located within the top 6 inches of the vessel.
(KS boiler code) also requires that the safety relief valve, on a unit your size, be mounted in a vertical position. The discharge outlet shall be located or piped in a manner that does not endanger person working in the area. (This means an elbow as close to the valve as possible and a short piece of pipe pointing downward to 6" above the floor to vent the release of water to a safe location) YOUR CODE MAY BE DIFFERENT, but this is just a good practice.

You got a plan, good luck with your project...
 
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Old 03-25-04, 09:19 AM
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ok, I have replaced the valve with the correct one specified by the manufacturer.
I am also awaiting delivery of my "Lazy Hand" Pressure gauge.
When the T&P valve discharged both times, it let out lots of water. Does this usually mean a problem with temp or pressure? I seem to remember that if the T&P drips a little water, it is a pressure problem, but if it releases several gallons, like mine did, it's a temperature issue.
Is this true?
 
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Old 03-26-04, 07:09 AM
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Caution on adding air to your pump pressure tank without knowing it needs more air pressure. The air pressure has to be 1-2 psi less than the cut-in pressure setting on the pressure switch controlling the pump. Run water until the pump starts and note the pressure it starts at. Shut off the water and note the pressure the pump stops at. Thats your pressure range of the pressure switch. Depending o the pump you have, you may have a 'constant' pressure device on the pump. Still the switch controls the pump and the air pressure in the tank is set according to the switch settings.

The 1-2 psi less air presure than the cut-in of the switch is with no water in the tank. Shut the water off after the tank, shut the power off to the pump, drain the tank, check the air pressure and adjust as needed.

When you drain the tank, that's a great opportunity to flush the tank. You do that by allowing all the water to drain out of the tank, thats when the dirt will come out (as the water stops flowing). Then, with the tank drain still open, turn the power on to the pump for a count of 5 and shut the pump off and allow all the water to drain out of the tank again. Repeat until no more dirt. Then check and adjust the air in the tank if needed. This should be done annually.

If you get water or water vapor when you check the air pressure, that indicates the 'bladder' is broken and you need a new tank

You use any means possible to add air but a compressor or portable air tank is best.

Gary Slusser
 
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Old 03-26-04, 07:42 AM
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I actually set the pressure in the tank when it was installed last year.
The pump cut-in is about 50, and the shutoff is about 70.
I set the tank pressure with it empty to about 48 if I remember correctly.
Wouldn't this tank act as an expansion tank for my Weil-McLain even though they about 50 feet apart? The only check valve is where the water main enters the inlet of the pump. The the pump discahrges into the tank.
I will clean the tank this weekend because we do have a lot of minerals in our water.
 
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Old 03-26-04, 08:20 AM
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The air precharge in a well water system (or boosted city water with a pressure tank) should be checked and adjusted as needed on an annual basis. The Schrader (air) valve is the same as on a car/truck or other tires, they or bladders leak, guaranteed. And I say one or two lbs less due to the air being hot when added and the water cools it substantially as soon as the water enters the tank. That causes less air volume and pressure in the tank. This compressed air provides your water pressure when your pump isn't running, so you want it right, not 'about' which might be 3-10 lbs more or less. lol It also minimizes pump starts that wear out all motors while making the electric meter spin wildly. And all that at least makes wallets lighter.

I can't see your system all that well.... so yes the pressure tank would act as an expansion tank BUT for the fact that your boiler isn't running NEAR the pressure your water system does. And doesn't your boiler have a pressure reduction fill valve on it and that separates your potable water from the boiler water? If not I think it should but I'm not a plumber and shouldn't be involved with this from that POV. Although I would assume your boiler should have an expansion tank, or two. And we see it has had the wrong T/P valve installed....

BTW, when your hot water recirc uses the cold feed line to return to the heater... that only does that when the cold water isn't being used somewhere else right? Because from here, that looks as if the normal direction is reversed. What does your hot water recirc pump do when that happens against the line pressure from your booster pump/tank?

Gary Slusser
 
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Old 03-26-04, 11:18 AM
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I think our signals are a little crossed.....The improper T&P valve was on the Weil-Mclain indirect hot water heater, which circulates boiler water around an inner tank.
The boiler does indeed have an expansion tank and a backflow preventer.
However, the domestic cold water (before it enters the hot water heater), does not have an expansion tank, unless you count the tank that is hooked up to the booster pump, like i said, it's about 50 feet from the water heater.
Supposedly, this autocirc system uses a very small pump (0.3 amps, or 33 watts) to move water from the hot shutoff valve under the sink back through the cold water line and ultimately back to the heater (or pressure tank near the water main). I have a hard time understanding exactly where it goes.
 
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Old 03-26-04, 01:30 PM
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You're signals are fine, it's mine that are crossed. I don't know anything about your system other than I had one somewhat like it years ago. Mine had a coil in a tank, not a tank in a tank. But I can't recall if the T/P was on the domestic hot water or the hot boiler water around the coil. Or if there was a cehck valve on the cold feed water line or not. Or if there was an expasion tank on the domestic hot side. It worked well.

I suspect your recirc is warming the cold water.... I wouldn't like that and would be running the water off to cool it. But the direction 'back' to the cold feed to the tank must be running against the flow to cold fixtures. Or that's what I see from here.

Gary Slusser
 
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Old 03-30-04, 02:45 PM
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Don't know if this is of any help, but I've been running an Autocirc for about 3 years now with no problem. Yes, it does put warm water into the cold line, but in our house it's only noticeable at the sink where the Autocirc is installed (kitchen - we never need cold water there...). It's unlikely, in my case that anything but cold water gets back to the water heater when the pump is running. Your case could be different. The configuration of your system is somewhat complex and even a small factor like the Autocirc might throw things off or expose a weak point. Did you replace the T&P valve that leaked or a different one (I got a little lost...)?

Doug M.
 
  #18  
Old 04-01-04, 05:12 PM
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confusion

There are two separate TP Valves on two isolated systems. One is domestic water, the other boiler water. If you drain the indirect hot water holding tank of about 5gallons from the bottom(this will be cold anyway, as only the top 2/3 of the tank is actually hot. This will relieve the pressure so that you can unscrew the old TP Valve and install the new one. Also...where the end of the dump pipe ends 6" above the floor, it may not be threded. Just in case place a small bucket under the pipe incase it dumps again....I think what you have is a failed or missing expansion tank. The one on the boiler is in no way connected to the same pressure as the domestic HW. Mine goes off at 150 PSI or 210F.... I think its more likely your thermostat is over heating the domestic hot water.
 
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