Tankless hot water sensor turn on stoker?

Does anyone know if there is a way to sense the hot water from the tankless coil, and turn on the stoker if it gets below a certain temperature (170)? The tankless works great with the exception of filling a soaking tub that is many gallons. I am considering installing a Boilermate tank, and adding another zone. However, thought I would pursue other options before spending the big $$$. Oil heats the boiler up fast enough to keep up, but there is too much of a lag with coal to heat the boiler in time for the hot water demand. The Boilermate will fix the problem, but thought it might be possible to turn on the coal burner sooner. I could turn up the low setting, but then have to keep the boiler really hot all the time. This is a waste of coal since there is only hot water demand this large once a night. I have the low limit set to 160 now.

Thanks,

Dave

Did you install the bypass line and adjust the valves to stop shocking the boiler? What are your aquastat settings? One purpose of the aquastat is to preserve hot water for the coil. It shuts down the circulator at 10 degrees below the low limit setting.

I'd McGiver it.... run a wire with a switch to the bathroom. Make it turn on the stoker. Turn on the switch half an hour before you want to fill the big tub. After tub's half full, turn off the switch, the rest of the fill will bring the boiler back down to the temp you started at.

Stoker-man,

I have experimented with the bypass line, and have found it works best with the valve fully open given the size of the boiler feed and bypass line. It does prevent the "shock" or fast drop in temp when multiple zones turn on. The tub is 80 gallons so there is not enough capacity in the boiler to heat this much water without the coal burner turning on in dependent of the call for heat. Pre-running the coal burner before filling the tub works. Freddy's idea would work great if I can run a wire the 100 feet from the basement to the 2nd floor of the house. I am having my wife turn on the heat in the bedroom first, wait 5 minutes then fill the tub. I may have to get the Boilermate tank.

Thanks,

Dave

An Ergomax tank is a completely different way of making/storing hot water. They are better than a Boilermate. You might have to go the indirect route because of so much demand.

Put a flow switch on the hot water out side and hook that up in parallel with stoker timer and wala problem solved.

Bill S.

Stoker-man,

I'll have to research the Ergomax! Thanks for the information.

Bill,

Interesting idea about the flow switch, but I wouldn't want the stoker to run everytime hot water is used. I thought about using a L6006C surface mount on the hot water outlet of the coil pipe, and have R-W wired in parallel to the timer. Set the L6006C to 170F, and if the hot water drops below 160 it will turn on the stoker assuming water is flowing. This doesn't work without hot water flowing... Would need a flow and temp sensor.

Fred,

The switch would be a simple solution, but have no way to get a wire up to the second floor bathroom.

Thanks,

Dave

You can get a wire anywhere! OK,OK, so you don't like sheetrock dust. Although, it would be just a thermostat wire, you might hide on the edge of wall to wall carpet & sneak it through closets. How about going wireless? Get a wireless doorbell, or a wireless light switch, a little bit of trickery & it would relay to an end switch for the boiler.

Do you have access to the pipe that goes to the second floor? If so put flow switch there. If not you might consider a remote control switch in conjunction with flow switch X10 http://www.smarthome.com/_/index.aspx dig around the site and see if something will work.

Bill S.

Went to the site and nothing about a flow switch can be found.

Sorry about that the Smart home site is for remote control devices. This is the site and prices for flow switches-http://dwyer-inst.com/Products/Product.cfm?Group_ID=167&Product_ID=368&sPageName=Ordering. I hope this helps you.

Bill S