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Thread: Hot coming out of cold... Boilermate/Coil issue?

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  1. #1
    DIY Member watson524's Avatar
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    Question Hot coming out of cold... Boilermate/Coil issue?

    Hi everyone,

    When we first built our house in 2002, we had just a Weil McLain Oil Fired Water boil using the coil for potable hot water and feeding our hot water baseboard heat. In January 2006, we added an Amtrol Boilermate. Our oil company did the install for us and I thought when we talked about it, they said potable hot water would just come from the boilermate and the coil would go away.... Over the years, we've had to turn down the boilermate because the hot water was so hot (we have it set around 130 now). In the past few years we've noticed that sometimes when we turn faucets on (doesn't matter if single lever in say the kitchen sink or dual lever in a bathroom) it'll be cold, then run warm/hot for a while then go back to cold. Also, our hot at full faucet strength is REALLY hot, like steaming....

    Ok fast forward to last week where our one toilet was running. I figured ok, time to replace the flapper, no big deal. Stuck my hand in the tank and the water was very warm... What the heck. So I turned on that bathroom fauct, HOT water coming out of cold..... So we start digging, no mixing valves under the sinks, figured it'd be odd for all cartridges in the faucet handles to be on the fritz so we called a friend who knows more about this stuff than we do.

    He went and looked at our boiler and said "why are you still using the coil?" Huh... dunno... that's what the oil company did, thought it was supposed to be taken out, that's been like that since 2006 with Amtrol Boilermate install. He said he would suspect that's causing the issue. The boiler is set at 160 low and 180 high. Water doesn't know what's calling for it, it just goes where there's no resistence. He said us turning down the boilermate to make it a better temp probably just exacerbated the fact that we're still using the coil for hot water and the boilermate is really just a big storage tank. Does that make sense? there's a mixing valve right above the coil that he didn't want to mess with not being an expert in these things but I told him I knew just the site where I could ask such things :-)

    I have pictures I can post if need be but basically, cold goes in to coil and over to boilermate on the bottom there and also to house piping. Hot pipe comes out of coil, goes to house piping and to the top center of the boilermate, then from the boilermate there's 2 other pipes, one to circulating pump and one to flow check valve (and a blow off pipe off the boilermate too).

    He said in his experience he would have expected to see the pipes to the coil cut off and left open (something about boiling steam out and going kaboom) and then the pipes from the top down to the coil cut and capped off.

    He said maybe the installer thought that if the boilermate crapped out, we'd still have hot water but that he thought the boiler could be turned back to 140 - 160 too since it'd be used for just heat if piped the way he'd expect to see it and then basically, the boiler shouldn't really run at all in the summer when heat isn't being called for since the potable hot is coming from the boilermate.

    We also ran a thermometer in various streams of hot water (kitchen and two bathrooms) and were at about 155 - 160 which he said is WAY too hot.

    Does it sound like that's why we're getting hot from cold at times and that our piping in the basement is goofy?

    thanks in advance! sorry for the long post, I just wanted to give as much info as possible. He also mentioned something about the boiler being able to do a cold start and then my eyes glazed over...

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    There should be a tempering valve on the outlet of the WH, and it may be on the fritz. that is what should moderate the water temp output from the WH to a safe level. Hard to say exactly what you have without being there or pictures. The logic board may need to be adjusted to tell the boiler not to maintain a certain temp to provide the water from the coil. Then, you could remove the inlet and outlets to it.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Member watson524's Avatar
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    The only valves on it are down on the bottom with the spigot where the cold line is which i assume is to drain the boilermate if need be. Then on the other side there's a black dial where 120 degrees is marked between the 3 and 4 and we have it JUST BARELY above the 3 and given that the hot water at the tap runs about 160 degrees which is much closer to the boiler coil setting and the fact that hot from the coil is still piped in to the house lines and the boilermate, it looks like something goofy is going on. plus things don't fluctuate unless we actually go mess with a dial. i've attached some pictures to hopefully clarify what i'm trying to say and can definitely take more if need be. thanks!

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    Name:  watson524_Boilermate.jpg
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    Last edited by Terry; 04-06-2011 at 10:33 AM.

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    In the Trades Tom Sawyer's Avatar
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    You need to get somebody to straighten the mess out. Cold water feeds the cold inlet on the boiler mate and the hot comes out the top. Two 3/4" tappings at the bottom are the boiler feed and return pipes. The old tankless coil should be either shut off or capped. The dual aquastat should have the low limit disabled

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    DIY Member watson524's Avatar
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    so my friend was right in that that coil connection should be gone. he said that the pipes into the coil should be cut JUST above that mixing valve and left open to air and then what comes down from the top should have caps put on them.

    is that legitimately what is causing our hot water to be SO hot because we're really still using the coil? (and thus more oil than need be... gggrrr.....)?

    and the aquastat, is that the gray box on the front that has a high and low? he did mention it's possible that control unit needed to be changed out but it wasn't his expertise so....

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    DIY Member watson524's Avatar
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    wait wait wait..... hot OUT of the boilermate DUH! (I just reread your post)..... well then here's more info... so we have a line out of the coil (that i have marked as hot in the picture)... that goes up and comes across and joins with the hot pipe going UP From the coil and into the hot water pipes for the house. so the valve right near the control box is open to send coil water up and the valve near the coil hot and boilermate top pipe come together is open so it's like it's drawing both at the same time. But again that may only answer why our water is so much hotter at the tap than we would expect but i don't get why the cold tap goes to warm/hot and then usually back to cold at various places.

    also, if you were using the boiler for heat only, what would be the setting? my friend mentioned he thought 140 was the accepted level.

    ADDED INFO AFTER "FIELD TEST". I turned the kitchen single lever sink handle to hot and left it run and went and watched in the basement. The circulating circuit on the argo panel for the boiler mate never came on. At 5 and 13 minutes, the well pump came on for about a minute. At 15 minutes the boiler kicked on because the low temp had dropped below the setting. The mixing valve thing between the hot and cold at the coil is all the way to the right (which I assume is closed. Not sure what any of this means.... but I wanted to report back.
    Last edited by watson524; 04-05-2011 at 12:05 PM. Reason: added more info

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