Indirect Tank Cycling

Dan_15

Hello, I just installed a new Buderus boiler system with an indirect DHW tank. I have never had an indirect tank before, and I am noticing that whenever I use just a small bit of hot water (like washing my hands) the indirect zone feels like it needs a refill and it calls for heat, and then the boiler starts up for a couple of minutes to satisfy the indirect. I have a high water mass system (converted from steam) with a lot of heat loss in my old home, so my boiler is sized fairly large with a Riello burner that is accordingly sized to burn 1.5 GPH. Is it normal for the boiler to cycle so much whenevrer I turn on the hot water? I am concerned that I am spending a lot of oil on frequent burner start ups. Can the indirect tank be better controlled with the logamatic controls? (I opted not to buy the logamatic). Thanks.

Weezbo

That is interesting.....i am not sure about this buh..

i have seen the buderas indirect and boiler off for like a day and hot water still roll out of them like no bollys business. maybe its piped different or something....

ScottMP

MAybe piping

what size is the tank ? If its a smaller tank, say 30 gallon, maybe it senses the drop if the faucet you turn on is farther away ? What kind of control is the aquastat ? Its possible that it is defective and has to close a differntial. Most have a at least a 5/10 degree differential that would allow a temp drop before calling.

The logomatic is allways a great idea.

Scott

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Lou Miller

My indirect (a 53 gallon Mega-Stor running off a Crown CT boiler, the Riello is set at 1.0 GPH) only runs, on average, 4 times a day. We need to take a couple of very long hot showers to make it come on. Even filling up the washer with hot water doesn't make it come on a good bit of the time. I'm no expert, but compared to what mine is doing, you've got some kind of bug to work out there. I'd be willing to bet it's in your aquastat.

Dan_15

Indirect Tank

Hi, thanks for your insight. My equipment is a Buderus G215/4 with Riello F40 and a Crown Megastor 40 gal indirect tank. The Buderus is controlled with a Honeywell high limit aquastat and the DHW tank is controlled the same way with a high limit aquastat that came with the tank. I have a Taco switching relay controlling the two zones that is setup for indirect priority. The cycling phenomenon seems to happen from any place in the house.

Al Corelli - Agix Associates

Can we get some pictures of the piping at the units?

Are the sensors for the aquastats fully inserted in the wells?

Dan_15

I will post some pics

I will post some pics of the setup when I get home tonight. The aquastat appears to be fully inserted into the boiler well, and I am not having any issues with that one. I have no idea if the aquastat is inserted properly into the indirect tank, because it appears to be simply attached to the side of the tank. Thanks.