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All-Purpose OWF Discussions => Plumbing => Topic started by: juddspaintballs on January 22, 2020, 04:59:07 PM

Title: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 22, 2020, 04:59:07 PM
I currently have a sidearm heat exchanger on my water heater.  It warms the water in the water heater nice and hot.  I installed that when I had hard and iron water.  I have since installed an iron filter and water softener.  I am at zero grains of hardness and no iron in my water.  So, now is the time to go with a flat plate heat exchanger, right?  I want to heat the water coming into the water heater so I have (essentially) unlimited hot water.


Should I remove the sidearm heat exchanger all together?  It would be a little more work to keep it plumbed into the system if I also ran the flat plate.  The water heater can maintain temperature, so I don't think I need the sidearm anymore. 


I have already flushed the crud out of the water heater since having soft water, don't worry. 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: wreckit87 on January 22, 2020, 05:12:40 PM
If the sidearm already existed, there would be no harm in leaving it there and simply adding the plate to the incoming cold line on top- assuming your sidearm is piped through the relief port on the side, that is. That'd get you the best of both worlds if you ever go long stretches without using DHW
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 22, 2020, 05:55:18 PM
I have 4 kids and I work a flex schedule.  We don't usually go long stretches without using hot water.  The sidearm is plumbed between the drain valve and the cold inlet.  I didn't touch the relief valve so it would be totally unaltered. 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on January 23, 2020, 02:47:34 AM
I don't know how much trouble it is to plug where it is teed into the water heater, but you could cut the stove lines off of it and route them through the flat plate. The sidearm could just stay there, but it will radiate a bit of heat.
You'll love the flat plate .
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: savebigmny on January 23, 2020, 01:29:54 PM
For reference I have a 3x8 30 plate HX on the incoming line.  With 170-180 boiler water temps it heats well water to 150 when running 1-2 GPM.  You can run the shower, washing machine, etc endlessly and the heat never slows down.  I don't have a mixing valve so it requires mentioning to people visiting that the water is very hot.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 23, 2020, 02:07:53 PM
Depending on the tank, itís worth mentioning that preheating the tank to those temps you might overheat the tank and need to reset the breaker when you decide to shut down your boiler! Better to go ahead and install the mixing valve and set it at 140
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 23, 2020, 07:46:15 PM
Slimjim, at my old house I had to reset the breaker on the water heater when I shut down the boiler because the water was that hot.  I was using a sidearm exhcnager with a stainless Taco 007 to circulate the tank.  This house, it's just passively heating the water inside, though I think it still gets up to the same temperature eventually.  I never have to reset the breaker on this water heater.  I do have a mixing valve to tone the water down to about 135 degrees, which is still pretty hot but not ~160 like the boiler's low set temp is. 



I'm looking at the 10 plate exhanger from Anderson's. 
http://www.freeheat4u.com/LB31-10-1-INCH-10-PLATE_p_172.html
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: RSI on January 23, 2020, 08:21:00 PM
Go with a 20 plate instead. A 10 plate will add a huge amount of head pressure loss.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 24, 2020, 03:20:57 AM
RSI is right on the head pressure, typically when I set them up I use a 30 plate and use a mono flow tee in the wood boiler loop for better flow.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 24, 2020, 03:22:56 AM
Juddspaintballs, so you sold the place in the mountains? I liked that location, Where did you go from there?
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on January 24, 2020, 06:01:56 AM
I had an interesting call yesterday, a 3x8 30 plate preheating into a 40 gal water heater was tripping something on the dishwasher (too hot). Anyone seen this before? It's a first for me. Wondering if I should just out a point of use mixing valve in at the dishwasher. They love the hot water in the rest of the house.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 24, 2020, 06:27:07 AM
130-140 degree water is pretty darn hot and with the plate exchanger they will never run out.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 24, 2020, 06:45:01 AM
Juddspaintballs, so you sold the place in the mountains? I liked that location, Where did you go from there?


Nope, still here in the mountains.  I used to live in Maryland and I had the Heatmor there, too.  I am trying to move in a year or so, but I'm not going far from where I am.  My parents bought a farm on the other side of the mountain and we're all going to live on the farm.  My dad has his boiler running there already and I'll be taking mine with me (again). 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 24, 2020, 06:50:01 AM
So that 10 plate exchanger I linked above is 12" long with 1" nipples.  The 30 plates that I can find are 3"x8" with 3/4" nipples.  Will the 30 plate still have less head pressure?
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 24, 2020, 07:26:23 AM
Badger Pipe has 30 plates with  inch ports. For some reason I thought you already moved after I dropped off your pipe years ago.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 24, 2020, 10:32:03 AM
Nope, still here in the mountains of WV.  It's been about 6 years since you dropped off the pipe.  When I move to the farm, it's just on the other side of the mountain so I'm not going too far. 





Badger Pipe 30 plate - $135.  I'll get that one.  Thanks  :thumbup:
https://badger-pipe.com/products/30-plate-water-to-water-brazed-plate-1-fpt-ports-w-new-style-brackets?variant=29491365201
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 24, 2020, 11:03:04 AM
I would like to vacation in that area once, meet the locals, learn how to make good shine.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 24, 2020, 01:20:52 PM
Well, when I finally do move to the farm, I'm going to need some Logstor again...
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 24, 2020, 02:44:44 PM
Can you make shine?
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 24, 2020, 07:31:13 PM
I have never tried to.  It is legal to do (for fuel).  I have a friend that makes fuel and stores it in mason jars, though.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 25, 2020, 03:47:12 AM
Maybe when I come down we can visit your friend as well?
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 28, 2020, 07:02:41 PM
Do I need a monoflow tee or will a pair of normal tee's work?  I'm obviously going to install isolation valves for the flat plate. 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 29, 2020, 07:10:08 PM
I've ordered the flat plate, I need to still order the 1" pex parts to make this work for me.  Regular tee's?
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on January 30, 2020, 01:29:41 AM
I use mono flo tees but if you space regulars away from each other to promote flow, they will work.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on January 30, 2020, 05:01:08 AM
Or just send it all through if it's large enough.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 30, 2020, 06:46:55 AM
It that 30 plate 5x12" exchanger by Badger big enough?  It has 1" ports.

https://badger-pipe.com/products/30-plate-water-to-water-brazed-plate-1-fpt-ports-w-new-style-brackets?variant=29491365201
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: RSI on January 30, 2020, 05:12:09 PM
That should be no problem putting in series. 30 plates have almost no head pressure drop. 20 plates are usually fine in series unless there are a lot of other restrictions in the system.  All the plates are in parallel so the more you have the less restriction you get.
If you had used a 10 plate then the monoflow tees would be needed or a much larger pump.

The size of the ports on a plate exchanger are usually not a bottleneck. Even 3/4" would not be a restriction unless you have full 1" iD or larger piping.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on January 31, 2020, 06:27:40 AM
Years ago I researched pressure drop on flat plates, and I would agree with RSI. I've used hundreds of 3x8 30 plate heat exchangers on systems requiring medium to lower flow rates/ smaller pumps and they've worked fine. 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 31, 2020, 06:35:08 AM
That's the way I'll do it, then.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: wreckit87 on January 31, 2020, 04:29:39 PM
The pressure drop across a 3x8 30 plate is 17 feet of head at 7 GPM versus a 20 plate 5x12 with 2 feet of head at the same flow rate. A 3x8 will destroy the flow rate in any system if piped in series, and unless you're living in a doghouse you'll need more than 2 GPM. The extra $30 you spend on a 5x12 will be recovered in 2 months of electrical usage by using a smaller pump
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on January 31, 2020, 07:36:05 PM
I bought the 30 plate 5x12 from Badger. 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on February 01, 2020, 06:37:47 AM
The pressure drop across a 3x8 30 plate is 17 feet of head at 7 GPM versus a 20 plate 5x12 with 2 feet of head at the same flow rate. A 3x8 will destroy the flow rate in any system if piped in series, and unless you're living in a doghouse you'll need more than 2 GPM. The extra $30 you spend on a 5x12 will be recovered in 2 months of electrical usage by using a smaller pump
Interesting, I looked up the same 3x8 30 plate and am seeing 1.4 psi at 7.2 gpm.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: wreckit87 on February 02, 2020, 11:08:20 AM
The pressure drop across a 3x8 30 plate is 17 feet of head at 7 GPM versus a 20 plate 5x12 with 2 feet of head at the same flow rate. A 3x8 will destroy the flow rate in any system if piped in series, and unless you're living in a doghouse you'll need more than 2 GPM. The extra $30 you spend on a 5x12 will be recovered in 2 months of electrical usage by using a smaller pump
Interesting, I looked up the same 3x8 30 plate and am seeing 1.4 psi at 7.2 gpm.

My Xlyem/ Bell & Gossett chart says otherwise. What brand plates are you using and where could I find that data?
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on February 03, 2020, 02:18:58 AM
Actually I was using the B&G chart on supplyhouse. It's no big deal, I may have been looking on the wrong model? I'll try to look it up tonight, got a crazy week ahead with a show going on.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on February 04, 2020, 03:15:18 AM
This is what I was looking at, 1.4 psi pressure drop at 7.2 gpm. ?
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on February 04, 2020, 03:11:10 PM
Flatplate and fittings are all here, now.  I need to anchor a 2x8 to my basement wall and bolt the flatplate onto that (brackets included with the flatplate).  I already put the 1" PEX crimp fittings and the 1"x3/4" bushings and 3/4" nipples into the flat plate.  I bought two lengths of braided stainless line in 3/4" for connecting from the house water to the flatplate and back to the water heater inlet.  I have two tee's and three ball valves for the pex so I can run the boiler water through the flatplate or bypass it as needed. 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on February 04, 2020, 07:12:01 PM
I'm curious what water temps you have going into the water heater. Should be around 140.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on February 04, 2020, 08:09:41 PM
Right now it's about 65 degrees going into the water heater.  After the flat plate, I hope it'll be nice and hot. 
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on February 05, 2020, 02:10:11 AM
After the flat plate is what I meant.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on February 06, 2020, 12:06:39 PM
I'll explain the pictures.  The flat plate had to mount horizontally because of the space I had. 


Boiler water comes in the right side of the flat plate and out the left side.  I have a bypass valve setup there just in case.  Cold domestic water comes in the left side and out the right side.  There's also a mixing valve on the hot output of the water heater so it doesn't come out as hot.  Boiler water that exits the flat plate goes to the water/air heat exchanger in the furnace and then back to the boiler.  I fired the boiler back up after this, so I'll know if I get hot water from the flat plate or not in a couple hours.


(https://photos.smugmug.com/Boiler-stuff/i-kBdmpwX/0/e87e0a5f/XL/20200206_132614-XL.jpg)


(https://photos.smugmug.com/Boiler-stuff/i-9jWX69k/0/1d856241/XL/20200206_132621-XL.jpg)
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: wreckit87 on February 08, 2020, 10:32:53 AM
Very strange Eldon, your chart says very different from mine for some reason. Even if you look at the technical specs on supplyhouse for that same plate, it says 8.6 PSI at 6.2 GPM. Odd they'd have 3 different sets of specs for the exact same plate!
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on February 08, 2020, 05:49:30 PM
It appears I have unlimited hot water, now.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: slimjim on February 09, 2020, 07:53:30 AM
Can you by any chance, turn it 90 degrees, they should be mounted vertically for cleaning and draining purposes.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: juddspaintballs on February 09, 2020, 05:39:19 PM
No room.
Title: Re: Flat plate and sidearm water heater heat exchangers
Post by: E Yoder on February 10, 2020, 04:45:40 AM
Very strange Eldon, your chart says very different from mine for some reason. Even if you look at the technical specs on supplyhouse for that same plate, it says 8.6 PSI at 6.2 GPM. Odd they'd have 3 different sets of specs for the exact same plate!
Don't want to derail this thread, we could start a new one.  I noticed the discrepancy on supplyhouse too, I checked and got  some numbers from GEA, they're saying 1.2 psi pressure drop for 7 gpm using a 3x8 30 plate. I dunno.