Multiple Issues Concerning PSI and Hot Water


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Old 04-11-11, 09:34 AM
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Multiple Issues Concerning PSI and Hot Water

Bunch of weird stuff going on. This all started when I gutted an old basement apartment out of my house. There was a bath down there and I just cut the lines to it and capped then off. When I did that I started getting leaky faucets, shower heads, the HW heater pressure relief valve blew, etc. I put a psi gauge on my utility sink in the basement and it sat most of the time at 60 psi but it would spike sometimes to 120psi! There was a leak in the old bath that I removed so I suspect the leak was providing a relief for the pressure. When I capped the lines I sealed the system and exposed the problem. The hot water is also acting weird now. For example on my shower mixer we'll say 6 o'clock is off, 9 if full hot. I usually set it to about noon when I shower. Now I turn it on it is almost too hot at about 2 for a couple minutes then cools down and I have to move it to about 10 and the HW doesn't last long.

Here is what I did this weekend. My feed from the street comes in the front of my house and all the plumbing is in the back and I only had 1/2" running across the basement so I wanted to upgrade to 3/4" anyways so I saw this as an opportunity. I ran new 3/4" PEX across the ceiling from the front to the back. Coming off the meter I put on a new pressure regulator, hooked it to the new PEX. At the other end I have basically a manifold, all 1/2". I cut the old 1/2" feed to that and reduced the 3/4" at this point to 1/2" to feed it. (I plan on upgrading all the lines eventually) I also added an expansion tank on the supply side feed into the HW heater. I also put a new pressure relief valve on the HW heater. Turned the water back on, everything looked good and was reading 60psi. I checked it last night and at some point it had spiked to 100psi. My shower mixer was still jacked up too. It seems all my changes did nothing to solve my problems.

Not sure what the next move would be. The HW heater is like 18 years old. Is it possible that could cause these problems? Also, when connecting the new pressure reg and PEX I realized my line from the street and the meter is only 1/2". After the meter I go to 3/4" across my ceiling then back down to 1/2". about a 50ft run. Is that all a waste of time since I have only 1/2" from the street? Will it cause any problems?

Sorry for the long post but I had to explain it all.
 
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Old 04-11-11, 10:15 AM
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You should not see pressures that high with the expansion tank on the HWH. If you read the instructions the tank should be set for house pressure. If you have 60psi then the expansion tank should have 60 psi or air. You do this with the system drained with no pressure on the system.

Your shower valve is probably a isolated issue. The spool may be going bad. What is the make of the shower diverter?.

Its ok to increase the size of your main. Pressure will stay the same(slight increase), but you get more volume. So you can flush a toilet and not see a drop in pressure.

As far as pex you should change the relief valve to a 100 psi. If you go over that you run the risk of blowing joints. That is code in most areas when changing to pex.

Like I said the expansion tank should take up the thermal expansion and you should not see 100 psi.

Mike NJ
 
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Old 04-11-11, 11:19 AM
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I agree with Mike, your expansion tank air cushion is likely too low. Now, the good and bad on the PEX. PEX has a slightly smaller inside diameter than the same trade sizes of either galvanized steel or copper. This means that your using the 3/4 inch PEX in conjunction with the 1/2 inch copper or steel service piping was good. When you get around to changing the rest of the piping I would advise continuing the 3/4 PEX to higher flow faucets like bathtubs and outside faucets. 1/2 inch PEX is okay for sinks provided the length isn't too long but I personally would use the 3/4 all the way and reduce at the faucet itself.
 
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Old 04-11-11, 11:58 AM
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I just installed the expansion tank out of the box. I made no adjustments or read instructions. I assumed it was already setup for normal situations. That might be my problem. I will check it when I get home.

I was thinking of another possibility, that HWH is old. If the thermostat or something was out on it and it over heated could it create too much pressure in the system? Would the expansion tank be able to take that much pressure? I'm going to turn down the HWH and see if that makes a difference.

The PEX joints blowing at 100psi concerns me so I need to find a solution ASAP before i end up with a flooded basement.

I want to put in a one bedroom apartment in the basement. That is what started this whole project. I currently have a 2br apartment on the second floor, 1br on first floor where I live and a future 1br basement. My complete upgrade plan is to put in 2 maybe 3 new HWHs, one for each floor. 2 would probably be sufficient I would think. I am going to run 3/4" PEX to as many places as I can get too. Most of the stuff on the first floor I can easily get to. The second floor apartment just has a 1/2" H/C set running up so I will run 3/4" to it until it goes vertical in the wall. I am a little concerned now that I only have 1/2" coming into the house to support all this. I would be worried that if all three showers were running it might just dribble out.
 

Last edited by landlord373; 04-11-11 at 12:15 PM.
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Old 04-17-11, 04:42 PM
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update

The expansion tank was not charged up. I drained the system and put 60 psi on it. I assume that is what I should set it at to match the house PSI. The instructions that came with the tank weren't real clear. I still have high pressure issues. At this point I am thinking it is my HW heater. I'm not getting much HW out of it either as I have already stated. I think it is shot. I'm going to replace it next and if that doesn't fix the problem then I am out of ideas.
 
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Old 04-17-11, 06:51 PM
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You still have high pressure issues and the expansion tank is holding air and charged?

I would say then the next thing is the PRV valve that you did state you changed.

The best thing to do is watch the pressure gauge and report back various pressures at different times.

Such as what is the pressure when you first get up in the morning with out turning on any water?

What is the pressure after the HWH has made temp and the burner turns off?

When the pressure is high, say 100 psi, when you open a faucet does it shoot down to 60 psi and stay there for awhile? ( This most likely would be thermal expansion)


Are there any valves in between the expansion tank that may be closed?

Was the PRV valve installed in the correct direction? It should have an arrow. Although I dont think it will work backwards but you never know.

There is not much that causes high pressure. Its either thermal expansion or pressure from the street. At night when the neighborhood is not using water street pressure rises.

Mike NJ
 
 

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