Hot water coil questions

I have a hilkoil coil in my keystoker koker but am not happy with it's operation so far. The issue seems to be: The circ. pump on the HW coil runs constantly. When hot water is turned on in the house, well water flows into the bottom of the tank and also into the supply line for the coil. The cool water does not pick up much heat from the coil and gets dumped into the top of the hot water tank which in essence cools my hot water. I can get the system to work OK by turning up the setting on my hot water tank but that seems counter-productive. I figure I could install an aquastat to leave the pump off until the coil return temp reaches ~125 or so but it seems that the aquastat would cycle quite a bit. Does anyone know of a control valve that could be used for this purpose? Something that could be installed inline and open when water temp. makes 125?

Charlie

Do you have your coil hooked into your drain and PRV valves of your hot water tank?

They will circulate a lot so the water doesn't boil in the stove, you can't leave the water sit in the coil too long. An aquastat might help a bit. maybe close down a valve some to slow the circulation down a bit.

Its not going to give you instant hot water, its made to help keep your tank warmer when not being used.
THey may temperature control valves.

Part of the problem is that I have an old oil fired hot water tank. There is no dip tube for the cold water supply. There are a total of 4 nozzles on the tank, two near the top and two near the bottom. The bottom ones are for 1) cold water in and 2) the drain and supply to the hilkoil. The ones at the top are 1) hot water out and 2) return from the hilkoil. I'm thinking about putting an orifice to restrict flow on the discharge of the pump. Anybody ever try that?

I've tried throttling the valve on the discharge side of the coil but still get enough flow to cool the hot water.

Charlie

You can add a dip tube into the *nozzle* on top from the hikoil...measure and cut it to end about 3/4 the way down into tank.

I have done it on mine and it solves the problem of cooling the upper portion of the tank. Don't be concerned with adding hot water 3/4 the way down in the tank...the water will stratify and make it's way up the hotter it gets and not be disturbing all the already hot water up top.

Hopefully you have a union there and don't have to cut your way in. All the *Big Box* stores carry dip tubes.

Can't really add a dip tube from the top. All the nozzles on my hot water tank come out the side. two near the top and two near the bottom.

Charlie

Depending on how bad you want this... you could try sliding in a piece of soft copper, bowing it ever so slightly as it goes in the *nozzle*. As what the factory dip tube is held fast by...you would need to flare the end that sits in the *nozzle*. When I did it w/ homemade parts...I flared a piece of CPVC plastic pipe for my dip tube.

Found something out last night. Pulled the check valve out of my pump and the water started circulating by convection. I think I'm going to just eliminate the pump.

Charlie

There is a lot more to hot water coils than meets the eye. As stated in my last message, removed the check valve and coil seems to work well by convection, but when furnace is calling for heat the outlet temp on the coil gets pretty high- almost 200F. Is this typical? do I need to install an aquastat to move the water when temp gets up in that range?

Charlie

Think I got it figured out. Installed a honeywell aquastat on the outlet pipe on the furnace. On at 130 off at 120. Works great. Fuel oil bill for Jan. and Feb. was only ~$120 (hot water only)