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...