inconsistent cold shower

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Old 01-31-10, 05:59 AM
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inconsistent cold shower

Hey folks,
First time poster.
First time homebuyer.

I'll try to keep this brief. I think I've diagnosed a lot of the issue, but looking for your input...

We bought our new home in Nov. Moved in on New Year's Eve after making many renovations. We immediately had water issues (the home was built in 62 and much of the water system seems original although we have a newish boiler (1995)). We had a day of no hot water in which I diagnosed a leaking and seemingly malfunctioning mixing valve. I replaced it with much fanfare and had a warm shower. In the following days I replaced the water pump sensor, a handful of gauges and re-pressurized the water tank to tackle water pressure issue and a short cycling pump. Once again we had hot showers. However, they weren't consistently hot. One shower would be hot and the next one cold and the following one hot. This could all be in quick succession or over a matter of days. Completely inconsistent.

Running down to the basement regularly I discovered that even when the shower (or sink) was cold the pipe coming out of the boiler was too hot to comfortably hold. However after it fed through the mixing valve it was luke-warm at best. Sounded like a bad mixing valve except it was brand new. More experience led me to notice that it is directly related to water pressure. When the pressure is low and the pump is about to kick on the water is cold. When the pump just shuts off the water is warm. It gradually gets colder until the pump kicks on and rebuilds the pressure. When we have 50 psi in the line the water is plenty hot. When we have 30 psi in the line the water is cold. It is always hot coming out of the boiler.

Here are my two thoughts:

1. we simply have a bad mixing valve. Even though it's new, it could be malfunctioning.

2. we could have a slight clog in the pipes in the boiler. If the pressure is high enough the water flows through the boiler just fine and and mixes properly in the valve and comes out at the proper temp. However, when the pressure drops, the water cannot force itself through the clog and only sends a trickle into the mixing valve which then gets mixed with cold and comes out luke-warm. The low pressure trickle would be enough to heat up the pipe going to the mixing valve, but then be cooled and sent out of the mixing valve slightly warm.

What do you think?

Of course there is always option 3: something I haven't thought of due to my ignorance.

My wife and daughter thank you in advance for their next hot shower...
 
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  #2  
Old 01-31-10, 08:08 AM
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Hi Lomir, welcome to the forums!

One thing that I want to clarify for other readers that have never lived with a private well system, Lomir is talking about the pressure tanks, and swings associated with them...

Lomir, sounds like your pressure switch is set up for 30 - 50 PSI?

I need to think on this one a bit... but it sounds like the mixing valves aren't 'pressure balanced'... I'm betting they are designed for constant pressure systems... like city water. They probably didn't give any thought to us poor saps with private wells.

When you installed the new valve, did you flush the lines out real well before putting the new one in? I'm wondering if some sediment might have gotten into the valve...
 
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Old 01-31-10, 10:30 AM
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I am not sure pressure has much to do with it. I have installed plenty of mixing valves on well systems through the years. The element is strictly temperature activated unless they changed. It was a thermal spring that opened or closed due to temperature.
Did you remove the element when soldering the valve in? Try turning the handle to hot, remove the handle and get past the stop and see if that does not make a difference.
 
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Old 01-31-10, 11:07 AM
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Thanks guys for your feedback.

NJ Trooper - You had to mention sediment didn't you...My opening post was long enough, but the one crucial piece of info that I left out was the sediment in the system. When I took ownership of the home, the previous homeowner had accidentally left one of the toilets running. It ran for three days straight. When I walked into the bathroom and heard it running I opened up the toilet tank and noticed it was filled with sediment. Lifting the seat there was probably 2-3 shovel fulls of sediment in there. Seriously!! I killed all the water and cleaned out the bowl and tank. Since then we have been pulling sediment out of everything. I have a feeling that is what was wrong with a number of the initial parts I replaced: Gunked with sediment. I was hoping I had it relatively cleaned out before I replaced the mixing valve but I may not have. Sediment is one of the reasons I think the boiler line have have a clog in it. Why not, it's been everywhere else! That being said, unfortunately no, I did not fully flush out the lines. That's what I'm thinking may be my next step.

rbeck - The only reason I mention pressure is because it is 100 percent consistent with testing. Under high pressure the water is hot. Under low, it is cool. I didn't think the mixing valve had any pressure sensitivities, but I also didn't know what one was until a month ago! I'm guessing the pressure has more to do with a sediment blockage, than the mixing valve. I assume the valve is functioning properly (unless it has become gunked too!). By the way, I didn't solder it in. It has three large nuts that hold it in place with gaskets. (It's a Taco 5000 if you want to check it out). It doesn't have a handle, but does have an adjusting screw. I have screwed it in and out and it does make a difference. The hot is hotter and the cool is cooler, but when the pressure is low, it is cool always.

Again, Thanks for the help so far...
 
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Old 01-31-10, 11:14 AM
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Did you install a sediment filter for the entire house? If not, you are still gettting sediment delivered into your house. They aren't very expensive to install or maintain.
 
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Old 01-31-10, 12:15 PM
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SHOVELS FULL? yikes! I don't think any 'whole house' filter is adequate to cope with that volume of 'stuff'... I think there are 'traps' available that will do the job though, followed by a fine 'sand filter'... then on to whatever other conditioning equipment you might have... that level of sediment will also prematurely wear out pumps and things... you might even explore the possibility of WHY you are getting that stuff up from the well... but this is off topic kinda...

Anyway... the reason I mentioned pressure balancing is because when I was researching shower valves for a project, I learned that there are two types... ones that react to temperature changes, and ones that react to pressure changes... and expensive ones that have both... apparently, the temperature compensated ones don't react fast enough to control temp diffs is for example a toilet is flushed while a shower is being taken...

So, I was thinking that perhaps the Taco valves simply didn't react fast enough to compensate for the pressure differences that occur as the well tank is being drawn down... and this could be partially to blame... but in view of the new info, I would explore the possibility of a blockage in the valve guts first.
 
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Old 01-31-10, 05:45 PM
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Well I don't believe the sediment is an ongoing thing. We no longer have sediment in our drinking water or in the the shower etc. The first week was a problem. What appeared to happen is that we have a very shallow well with a jet pump. Since the toilet ran three straight days it appeared to have run the well down which then drew up the sediment. I'm not convinced it has been an ongoing problem or will continue to be one, but instead was a one time occurrence due to the fact the toilet was left running so long. That being said, I am also not 1oo per cent convinced that it isn't on going. It could be. However, the evidence on sediment in the water appears to be gone but there is undoubtedly residue sediment in the various nooks and crannies of the system. Perhaps I will take out the new valve, inspect it, clean it, and put it back. I just didn't want to go through all that if it was barking up the wrong tree.
 
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Old 02-10-10, 04:05 PM
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Hello everyone first timer here. It seems as though i have the same issue as Lomir except for the sediment and i'm on town water. I have a Burnham only 5 or so years old. Have replaced the Taco 5000 with a Taco 5000-2 still no resolve. I feel your pain Lomir 110.00 for a mixing valve I thought was the prob but nooooooo. Im in the trades and have been asking around... Its killing me and im not going to stop untill I get it right. I'll let you know if I find out anything and I hope you will do the same.Untill then good luck.
 

Last edited by newhamp; 02-10-10 at 04:26 PM.
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Old 01-24-15, 06:38 PM
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Did you guys ever come up with a solution to inconstant water problem. I am having the almost identical issue and came across the thread via a google search. I already had the mixing valve replaced and the issue persists.

The wrinkle on my end is that the hot water heater also powers the heat in the apartment and when the heat is on, the inconstant hot water problem is far less prevalent - there is a pump that runs when the heat is on, which maybe has something to do with the pressure.

Hopefully someone out there has a solution.
 
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