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[Strawbale Builder]

Move the plate hex from the cold to the hot supply line so you are not dumping the hot water leaving the plate into the water heater. When you turn on any hot fixture the water leaving the water heater will flow through the plate hex directly to the fixture and deliver very hot water, always temper with a mix valve. Make sure the fluid flow in the hex between the boiler water and dhw are in opposite directions.

[shepherd boy]

I would not move the heat exchanger. If the water entering the water heater is not a lot of difference from the exit you will not gain much. mlappin is right on cleaning the heat exchanger. RSI is right on needing to check flow from the boiler. Check your temp where it leaves the boiler the same way you check it at the house. Hawken is built on the old Global design and I have seen Global units with poor circulation within the stove and exit water not as hot as aquastat reading, not saying this is happening but I would check it.Also if the heat exchanger is plugged tight on some of the slots, the cleaner will not get it. It will only clean the slots that are at least have some flow.

[kommandokenny]

Went through all this crap myself.

Sidearm solved my problem.
86 the plate!!!

http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=6915.0

[trz]

What sidearm do you use?

[Strawbale Builder]

We have installed for quite a few dairy farms that need very hot water for equipment washing two to three times a day. Because of the large daily process heat demand most all of them burn year round. We found the best way to meet this demand is to put the plate hex on the hot side bypassing the tank. Been doing it for years, works great. Also install the same way for our residential customers but always include a mix valve. In a plate hex fluid flow must be in opposite directions or it will be ineffective. If the plate is plugging up that is a different issue. Cleaning the plate often to keep a proper flow rate can be a pain, so a side arm could be the answer. We still use side arms in certain situations, usually 80000 btu for residential.

[mlappin]

We have installed for quite a few dairy farms that need very hot water for equipment washing two to three times a day. Because of the large daily process heat demand most all of them burn year round. We found the best way to meet this demand is to put the plate hex on the hot side bypassing the tank. Been doing it for years, works great. Also install the same way for our residential customers but always include a mix valve.

Thats pretty much what I did with mine, I also use a sidearm as an experiment to see just how much heat a sidearm can pull out of the boiler water. Works reasonably well, most of the time the sidearm can keep up, I have an aguastat that starts the pump for the secondary loop for the DHW anytime the water is below 140 coming out of the water heater. Water that is heated by the sidearm leaves the hot water heater and enters the plate, if temp is high enough no problem, if not the pump on the plate secondary loop starts.

[patvetzal]

You have pinpointed your problem. You have no way to reheat the water once it makes its way into the 40 gallon heater. While you could get a $300 side arm, you could also hook your plate up as a thermosiphon the same as you would a sidearm.
Pipe in a loop from the bottom of your electric heater and connect it to the top, where the relief valve goes. Do not remove the relief valve, just install a brass T fitting under it. This allows the heated water to return to the tank while stopping it from "short circuiting" . The bottom connection (to the plate) can just tie into the cold water intake of the tank. As long as the plate is mounted lower than the tank, it will thermosiphon and fill the tank with hot water, but that water can wind up at the same temperature as the OWB unless there is a mixing valve.

[RSI]

If it has never worked right since it was new then it is probably not a plugging problem.

You could get a sidearm but adding a recirc pump would be easier and cheaper and work better. There is another problem with the system though which would be better to fix that changing out the hot water heat exchanger.

Also, if the water heater is fairly old, there may be a lot of sediment built up inside that could plug a sidearm fairly quick. Electric water heaters are usually worse for that too.

[trz]

Where would i find a recirculating pump and how is it plumbed in?

[trz]

Patvetz
Wish i had a diagram of that!

[RSI]

Put a tee before the plate hx and one either at the drain or another place in the tank. Lower will get better circulation. Then pump water from the tank to the tee before the plate HX.

Have you checked the temp of the OWB water after the plate hx when the hot water is running? You should really make sure you have enough flow.

[patvetzal]

Wish I could post pictures....