Re: odd hot water problem
sorry been away for work but back now and I think that I found the water pressure problem but know that the hot water problem won't go away since it's been a problem from day one.
I went to take a shower the other day and very low pressure so decided to check out everything, turned on faucet near shower low pressure, went downstairs turned on faucet in kitchen low pressure, went down stairs to washing machine turned that on low pressure then heard a gurgling noise in water heater pressure went back to normal. It has to be the water heater.
So leads me to believe that there is something wrong the water heater, I need to check warranty but it's either 9 or 12 year warranty so seeing that it's about five years old I'll look into having some check it.
I think at this point I'm going to install a point of use electric on demand heater for the shower so we can finally take consecutive hot showers.
Re: odd hot water problem
I want to re-summarize, just to be sure I'm not missing anything:
-Occasional pressure/temp issues in bathroom water supply only, rest of house, no issues.
-Only have pressure/temp issues in the morning, and it gives an odd sound when you have the issue.
-Started happening ~14 years ago, ok before.
-Have replaced WH at least a couple times since then.
-Shower mixing valve replaced since issue started.
Based on this, the logical conclusions are:
1. Piping prior to WH is OK, since rest of house has no issues.
2. Water supply after WH is only a concern in piping running directly to bathroom and not shared w/ other rooms.
3. Unlikely the shower valve, as you replaced it... (but for the sake of absolute confidence, we'll leave it as 'possible')
That said, I have two things that come to mind. Maybe they're reasonable, maybe way off target, but never hurts to bring them up:
First, is some sort of blockage that is intermittently flapping to a more closed position. That seems unlikely to me, since you are saying it most often occurs in the morning, but at 10+ years of dealing with it, you may want to look into just replacing that line.
Second, it may be a pressure/suction issue in the line somewhere. I would check the piping where it goes into the mixing valve. Look as far inside as you can see and make sure that someone didn't change pipe size at any point. Maybe some weird pressure variation in the morning when the pipes are coolest. You may also want to throw a water hammer arrestor on the hot water supply in the bathroom (sink would probably be easiest to access and it sounds like the whole bathroom is on the same line). If plumbers came and looked/listened and didn't think it was water hammering... probably isn't, but, again, never hurts to have -something- to try.
Since the problem seems to be with getting hot water to your bathroom, I would really only be looking at that line first. Also make sure you don't have any odd 'inline' filters... you never know what previous owners have thought was a good idea.
4 cents. All yours!