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Author:
BillM (NJ)
I am desperate and need your help.
Our oil fired boiler (cracked tank) died last week, and we had a contractor install a new Weil Mclain boiler and indirect hot water tank. Since the installation, the heat has worked fine, but we have had issues with the hot water. The contractor has been onsite 3 times, and we still are having problems.
The hot water in the shower runs hot for a few minutes before gradually turning cold. The contractor seems to think that the issue is related to the thermostat, and is replacing it. I believe otherwise.
1. The pipe that heats the tank and goes into the bottom of the side of the tank is hot to the touch. The contractor manually opened the thermostat controlled valve to insure that we have hot water until he resolves the problem.
2. The return pipe running out of the top/side of the tank is also hot to the touch, but not as hot as the bottom.
3. The pipe on the top right of the tank (domestic feed?) is cold to the touch.
4. The pipe on the top left of the tank (domestic hot water) is luke warm.
I am not an expert, but I have a modicum of common sense. If this was a thermostat issue, the water would not get hot at all. Since the thermostat valve was manually locked in the open position, and the feed and return coming from the boiler are both hot, it means that the outer tank is getting hot, thus heating the domestic hot water. I think the tank was piped incorrectly. I just want to have the contractor fix the problem.
Is it possible that they accidentally switched the domestic hot water and cold feed during installation?
Any ideas that I could give to the contractor?
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Author:
North Carolina Plumber (NC)
Sounds like it is piped correctly, what is the high- low temp settings on the boiler now? What brand is the indirect heater? Does the zone valve turn on the circulator pump? Do you have a temp gauge on the indirect heater? So far I'm inclined to believe the thermostat could be at fault. It could also be a wiring issue with the zone controling the indirect.
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Author:
BillM (NJ)
Thanks for the response! Here are the specs on the tank:
[weil-mclain.com]
Boiler max/min: 190/175.
Indirect is also weil-mclain coil-less
Zone valve manually set to open. Water is circulating - feed pipe from boiler and return pipes are hot to the touch.
Temp gauge on tank set on max and attached to zone valve.
I spoke with Weil-mclain after an hour on hold. The tank is coil-less. There is an outside heating tank and the domestic water tank is internal. The zone valve was left open by the contractor as a temporary fix, and the boiler supply and return pipes are hot to the touch - the external tank appears to be heating correctly. The Weil-mclain guy thought it was a water stratification problem, and suggested 2 possible causes:
1. The contractor switched the domestic inlet and the domestic outlet oulet. They both come in on the top of the tank. The inlet puts domestic cold water into the bottom of the tank via a "dip tube" and the domestic hot water outlet to the house is piped from the top of the tank. Switching these pipes would mean extracting colder water from the bottom of the tank. The water piped in at the top would sink, cooling off the water being extracted from the bottom.
2. Weil Mclain ships a spare "dip tube". If the contactor put this on the domestic oulet, the system is pulling hot water from the bottom of the tank, and injecting cold water into the bottom of the tank. (This is my guess.)
Either of these seems to make more sense than the thermostat. If it was a thermostat problem, the water would never get hot, or would only be luke warm, and the pipes from the boiler would not get hot - particularly the return. I am getting limited amounts of hot water that gradually turn cold after 2-3 minutes. If the boiler supply and return pipes coming from the boiler are hot, it means that the outer tank is hot, and all of the water in the domestic tank should therefore be hot. I am getting some hot water, which leads me to believe that I am pulling domestic hot water from the bottom of the tank. It starts hot and then gets cold. There is no way for the tank to go empty in 2-3 minutes of showering.
The contractor installed a new thermostat today. We will see if it works.
Edited 1 times.
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Author:
North Carolina Plumber (NC)
Good info there, I tend to agree with you now, the syptoms you describe sound like a dip tube problem. The indirect heaters I install have the cold in on the bottom and there is a coil inside. Just manually opening the zone valve won't turn the circulating pump on. Does it have a dedicated pump or does it share a pump with your heating zones?
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Author:
packy
yikes, if you have a contractor who installed a dip tube on the hot water outlet, time to look for a more competent contractor.
is there a recirculating line on your system?
has someone felt the hot water outlet as you are running out of hot water?
the thermostat knob is on the top of the tank but the actual sensor is located about 2/3 down. maybe something is messed up with that?
is the boiler a weil mclain gold series or weil mclain ultra?
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Author:
Scott D. Plumber (VA)
I "third" the motion on the dip tube. This sounds like exactly what would happen if the dip tube were to be missing or break during installation (Rare)
Everything would look right on the outside and "be" right. but it would do what you are describing. Post a pic if you can.
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