HX: Copper Coil or Plate?

[jebatty]

With the cost of copper tubing for hx vs the cost of flat plate hx's, I'm wondering what are the +/- of copper tube vs plate hx. Also, are there distinct benefits and disadvantages depending upon application? I realize the flat plate requires a second circulator pump.

I bring this up in part because with 110 input water to my plate hx, and 170 boiler input, my hx output is 165, just a 5 degree difference. As hx input rise to 130, hx output is nearly 170. I'm using a 5 x 12 x 30 plate hx, 1" inlet/outlets, Taco 007 on the output side, Taco 009 on the boiler input side.

 

[webbie]

This is really old info, but the engineers at Tarm patented a flat plate HE which they claimed worked much better than any copper coil or other HE. Others know a lot more about this, but I think plate HEs are the wave of today and the future.

 

[Nofossil]

I think you can find pretty high performance flat plate HX, but as you point out, it's another pump. So many tradeoffs.

 

[NHFarmer]

I know this is an old thead but it seems to be relevant.Jim have you had any problems with the hx plugging up,do you have any filters or do you do any maint.With the price of copper I am beginning to think the flat plate may be the way to go.I have been looking at many options with copper and I can't seem to be able to beat the price of a flat plate hx.How do you plumb in the second circulator pump?

 

[jebatty]

This is really old info . . . plate HEs are the wave of today and the future.

No disagreement, just brought this up again after seeing the posts on the 100's of feet of coil and again wondering why.

. . .any problems with the hx plugging up, do you have any filters or do you do any maint. How do you plumb in the second circulator pump?

No apparent problems of flow rate after nearly one full season of heavy use. I have a high temp water filter and use 50 micron filers, pretty inexpensive, mainly because my current tank is a used fuel oil tank and I was concerned about crud in the tank getting in the line and plugging the hx. I do not filter the boiler side, which is pressurized. As currently an open system to storage, rust in the tanks is producing a rusty slime on the filter, and I suspect some is in the hx too. The hx is designed to create some turbulence in its innards, both to maximize contact and heat transfer and to prevent blockage. After this heat season I will remove the hx (installed with unions) and pump a cleaner through it. Operationally, any decrease in performance of the hx has not been noticeable.

Copper or pex lines would be subject to a similar issue, as any rust, minerals or whatever in the water would also attach to the pipe walls and decrease heat transfer over time.

Many ways to plumb, and my situation is a little unique because the tank is in my shop, and I use the tank as a large radiator to heat the shop. I also have a manual diversion to a unit heater to get immediate heat if the tank cools down too much between boiler firings. Because the tank itself is the radiating heat source, I only pump when the boiler is operating. My control is simple: an aquastat on the boiler return line (with a Termovar mixing valve), set at 150, which activates both the boiler circ pump which only runs a loop through the hx, and the circ pump on the other side of the hx to heat the tank (and diversion to unit heater). The tank circ pump is on the floor and fed from the bottom of the tank.

Simplified Diagram

 

[muleman51]

Jim , I like your simple design. Where do you pull your supply for you home heating needs. I need to add storage to my boiler that is if I can get my adobe boiler issues worked out. I'm thinking of using a bulk milk tank for my storage, but how do you keep the water from getting all skunky do you have to add lots of chemicals or will 160-180 degree water stay clear. I know a hot tub sure goes bad if you don't stay on top of it.

 

[jebatty]

Jim , I like your simple design. Where do you pull your supply for you home heating needs. I need to add storage to my boiler that is if I can get my adobe boiler issues worked out. I'm thinking of using a bulk milk tank for my storage, but how do you keep the water from getting all skunky do you have to add lots of chemicals or will 160-180 degree water stay clear. I know a hot tub sure goes bad if you don't stay on top of it.

Note that I use this to heat my shop, using the tank as a large radiator, so I don't pull heat from the tank. Some other threads discuss in detail how to pull heat from storage. I was concerned about the storage water getting skunky, especially in an open system. I do drive the tanks up to 150-165, and maybe at that temperature once in awhile all the skunk gets cooked. In a closed system I'm thinking it will be less of an issue, as all oxygen will be depleted and the environment will not be conducive to growing anything, much like a house water system fed from a well.