DHW tanks to accept a heat exchanger

[timberbuilt]

I am not really interested in a boilermate because I would like to have back up electric DHW, therefore I am looking for an electric DHW tank that would be acceptable for heat exchange. What are my options for heat exchange and what would an electric DHW tank need to have to add a heat exchanger? Please steer me in the right direction.

Also, where would be a good place to find additional information about sidearm heat exchange?

Thanks

 

[webie]

So are you looking for something like this ?http://www.google.com/products/cata...ct=result&resnum=3&ved=0CCIQ8wIwAg#ps-sellers

 

[dogwood]

Nice product Webie. Would you or anyone be aware of any company that make a similar product, electric dhw heater with built in water to water hx, in a 30 to 40 gallon size. At one point I was looking for just that but couldn't find anything. Just curious. The Raritan model your link leads to maxes out at 20 gallons.

Mike

 

[timberbuilt]

Webie,

Thanks for the link. Like Mike, this would probably work in my situation if it was larger.

My original plan is to get a run of the mill electric hotwater heater and put a sidearm heat exchanger onto it. Can all run of the mill hotwater heaters accept a sidearm?

 

[webie]

Webie,

Thanks for the link. Like Mike, this would probably work in my situation if it was larger.

My original plan is to get a run of the mill electric hotwater heater and put a sidearm heat exchanger onto it. Can all run of the mill hotwater heaters accept a sidearm?

yes they can

 

[RobC]

Superstor has them http://www.htproducts.com/literature/lp-195.pdf
I wasn't able to see what webie was showing. Superstor also has the same with 97% efficient gas. Electric hot water will make the meter spin. I had a 1 gallon heater for my shop, slop sink and I just found out that it was costing me $40 / mo just in stand by. I maybe would wash my hands 12 times a week out there.... Thing broke and didn't bother replacing it for a couple on months and holy $h!t my electric bill dropped $40. Put in on demand electric and it is perfect.
Rob

 

[dogwood]

Thanks RobC. You know I looked all over the the internet trying to find one of these a few months back, before going with an external flat plate. I wonder what the turnaround time would be to reheat one of these internal hx DHW tanks with hot water from the boiler, or storage; and if it would be anywhere comparable to what you can get with a flat plate hx. It sure would have been a simpler operation.

Mike

Geez, I just checked out the price on these at http://www.jtgmuir.com/pricing/HTP-JTG-Pricing_09-01-08.pdf. Least expensive SE model with electric backup was over 1800+ dollars and I don't think that included shipping. Makes the flat plate with two circs a bargain. Maybe if we hit the lottery.

Mike

 

[RobC]

I have a Glass lined Superstor 40 that is just a storage tank. I run it with a mixing valve on the out flow of the DHW so I can store water at higher temps allowing for more capacity or usable hot water. How long to bring up to temp. 1st we almost never run out. The one thing we don't do is to take 2 showers at the same time. We usually will stagger between showers 10 or 15 minutes and all you get is as much hot water as you could want. Note on showers. We all enjoy long hot showers, very active family that enjoys the relaxation !
The SE is a Stainless tank that's why the high $. Any of your Solar storage tanks would have simular set ups as to what your looking for.
There a few ways to get DHW what is your system set up ?
Rob

 

[dogwood]

RobC, I'm going with a GEA 20 plate flat plate hx with a Laing recirc pump servicing the DHW side, and a Grundfos 3 speed servicing the boiler water side. I'm connecting to a standard A.O. Smith propane fired DHW heater using the drain and prv ports. Aquastat to turn on both pumps is near the drain port. I am using a tempering valve like you so I can store hotter water. Also will incorporate some Webstone valves HotRod suggested to facilitate cleaning the flat plate of hard water deposits on the DHW side, and a wye cleanout on the boiler hot water side. I'm hoping for a fifteen minute turn-around time, like you have, between showers.

Been laid up following disk surgery since November so these are just parts in boxes until mid-April when I'm told I can start doing physical work again. Can't wait. Whole system is going in then for next season. I'm filing away your information for future upgrades. I'll try and search out those other Superstor(?) solar storage tanks you mention. I needed the electric backup because my job is taking me away from home three days a week now and I wanted to be sure my wife had DHW if the boiler wasn't being run, as well as for use in the summer months if we didn't want to burn wood then. Thanks

Mike

 

[in hot water]

www.butlersunsolutions.com builds a small HX that drops into a water heater tank. Small capacity but you could double them up. i've used them tom "pull" heat from a DHW tank to supply small radiant systems.

hr

 

[RobC]

Your system set up is just wood and storage ? How do you get DHW now? Could you cut in a tankless electric or propane ? Then you not storing any hot water and when you want it you get all you want. Houseneeds.com has a bunch to look at online. Some of the bigger electric units need multiple power supplies be careful need lots of wire and 3 X 2 pole breakers. Some of the propane are sweet, they have electronic ignition. Our electric rates around Boston are such that we try to avoid electric any thing. Short money up front but that's about it.
Rob