Print

[Scott7m]

I install a 20 plate exchanger with 1" ports.  Never heard of anyone say the water wasn't hot enough or that they ran out of hot water either.  It's very consistant and it makes for a easier install with no mixing valve and the other garb.  My OWB is currently set on 158 degrees and my DHW is HOTT .  You have to turn the cold over half way to take a shower.

[willieG]

I install a 20 plate exchanger with 1" ports.  Never heard of anyone say the water wasn't hot enough or that they ran out of hot water either.  It's very consistant and it makes for a easier install with no mixing valve and the other garb.  My OWB is currently set on 158 degrees and my DHW is HOTT .  You have to turn the cold over half way to take a shower.

I run mine through a home made exchanger and like Scott i have no mixing valve. That can be dangerous if you have young, kids as water above 160 can scald young skin in a second, 130 takes about 30 seconds, so you can see a young child may not be able to move their hand out of the way in 1 second, but in 30 seconds they have time to react
Some newer taps have built in tempering valves. Like I said, I too run my domestic water without a tempering valve but i put this warning up to caution anyone going to do this to think seriously about it before acting
happy heating

[tulenutn2o]

I put a tempering valve in but haven't used it.  I personally love the control at the faucet over how hot my shower is. Not to mention, the dishes are a heck of a lot cleaner now.

[1grnlwn]

I don't know what a flat-plate cost but why couldn't you move your side arm to the HWH input and turn on the juice (electricity) .  My boiler has DHW coil and  can heat a lot of water but we leave the electric on to smooth out the cold spots or for emergencies.  The hot water heater kicked out once and we noticed a reduction in DHW probably due to being 75' from boiler.

[RSI]

I install a 20 plate exchanger with 1" ports.  Never heard of anyone say the water wasn't hot enough or that they ran out of hot water either.  It's very consistant and it makes for a easier install with no mixing valve and the other garb.  My OWB is currently set on 158 degrees and my DHW is HOTT .  You have to turn the cold over half way to take a shower.

I sure hope you don't install them like that for other people. If you do you are crazy. You could get sued real good when someone's kid get's scalded. All it would take would be to leave a faucet trickling overnight and the water would come out of the faucet at the boiler's temp.
Now if it is your own and you know what to expect, that is fine. I have the same setup on mine but with a 10 plate and it works real well.

[RSI]

Back to the original posting, is the sidearm one that just has a single 3/4" pipe through a larger pipe? If so you probably just get plenty of hot water by just putting a decent sidearm on. If that doesn't do it adding a recirc pump will.

[Ridgekid]

I know this post is over two months old, but as proof I have been reading about this DHW thing I would like to continue from here:

1. I really can't install a Plate type HX due to well water.  (It would scale up).
2. A sidearm sounds good but I'm having a hard time seeing how cold water entering through the bottom, gets hot and returns to the tank by gravity.
http://www.centralboiler.com/Tech/C100.pdf

I know there's an option to add a circ pump, but to me that defeats the purpose of reducing my electrical dependance. OK I know it's minor, but geez it's also an added maintenance component.

First, let me say this is for winter time use only. I don't plan on operating my OWB year round.

So bare with me a minute. (Maybe I'm overthinking this). A sidearm is mounted vertical with OWB suppling heated water from bottom to top.
Why can't the Domestic cold water be routed directly into the sidearm at the top and then return to the bottom of the HWH? Isn't this how cold water in normally entered into a HWH, through a long tube to the bottom of the tank inside the HWH?
Is it too much of a load on our OWB's? (I doubt it, but thought I would add this to let you know I was thinking)
Is it because the HWH (in this case 50 gallons) would get cold before use? What if I left the electric on year round. Wouldn't it provide me a faster recovery mounted this way? (when the OWB was running?).

What I was thinking: (NOTE: I have 20" of copper pipe from the house shutoff valves to the top of the HWH.
 http://outdoorwoodfurnaceinfo.com/forum/index.php?action=media;sa=media;in=35
I would still install a thermostatic valve. I have CPVC pipe through out the house. Not sure how much heat they can take. That and the fact I would not want to scald anyone.
I would add three shutoff valves to the cold water side. One to the sidearm, one to the tank and the one going to thermostatic valve.  This way I could control which way the water was going in winter and summer.
I would add three T's. One supply to the sidearm and one supplying the thermostatic valve for the cold domestic water and one for the side arm at the bottom of the tank.

OK-What am I missing?

[tulenutn2o]

Ridgekid, I have a sidearm at the water heater(as a lot of users on here do too) and let me assure you, it does work. I ran my supply from OWB to top of sidearm first, though. I had to replace my leaking water heater anyway so I went from a 50 gal. to a 40 gal with reservations. Worries were unwarranted. I have yet to run out of hot water from this set-up.

[dirtryder]

Ridgekid,
I have a 10 plate HX AND well water. Only for winter use....but.... still burning now .....I have used it for 2 full seasons and have had no problems with it. I also heard the scaling stories but so far so good. I also heard a little vinegar and water flush will clean it out very easily, so I plumbed it with this in mind. Don't worry about the CPVC pipe handling the hot water because you MUST install a mixing (tempering) valve if going this route as not to hurt anyone. I bet that you would have to worry more about your fixtures (faucets) with straight boiler water temp than the CPVC.  I ran mine without the tempering valve for about a week..........with no little children and knew it was only a matter of time for someone to get burnt. The only thing I can say is......with a sidearm, you have "X" number of gallons of hot water in your tank and if you deplete that you go cold (just like normal) BUT, with a plate HX, I have on demand hot water all day long

[Ridgekid]

My other fears are breaking connections loose on a 18 year old water heater. When I start a project like this I have to keep in the back of my mind "What are you going to break" and "How much will cost tof fix it if it does break".

[dirtryder]

My other fears are breaking connections loose on a 18 year old water heater. When I start a project like this I have to keep in the back of my mind "What are you going to break" and "How much will cost tof fix it if it does break".

When you install the plate "downstream" of your hot water out (where it needs to be) you do not have to touch the connections at the water heater.

[RSI]

I was talking to an HVAC contractor and he told me he tries to avoid mixing valves whenever possible because they always start to leak and stick after 4 or 5 years.
His suggestion was to have a thermostat controlled zone valve control the temperature of the water in the tank. I don't think that would work very well because the way side arms work the water is usually cold at the bottom and way hotter at the top. The hotter water allows for more capacity because it is adding cold and not taking as much out of the tank.

My idea is to put the side arm between the cold and hot pipes to the tank and pump the water. This should heat the tank to the set temperature and give a lot faster recovery time. A shell in tube type heat side arm would be needed (or a plate would work) because a regular straight through would not have enough heat capacity to keep up. The pump would only run when the water needed heating. Only a few cents of electricity per day.

Another way to do it would be to put the side arm in series with the cold water inlet and pump water from the hot line to before the side arm. This would make the pump not need to run much and give faster recovery but there is a slight chance of scalding if a faucet is left trickling. (if no mixing valve is used)

[donahuej]

I agree on the mixing valves..too temperamental.  I went with a thirty plate mounted in my crawl after my tank.  Not quite ready to fire it up for the first time just yet - I'll keep you posted on how I make out.  Running out of how water - two teenage girls and two Jacuzzi tubs - was the reason I went with a big plate after the tank - fire in the boiler there will be hot water - and all the plumbing is down  below I don't have a ton of room in my new my water heater...

Jamie

[RSI]

You have a 30 plate after the tank and no mixing valve? I hope you have some thick skin. lol
You will have water coming out your faucet pretty much the same temperature at the boiler water. If you put it before the tank then it will be a lot safer as the tank will buffer the temperature. I have a 10 plate before and the water coming out the faucet gets up to 140 at times.

[merrellroofing]

I just bought a used 6048 that came with a sidearm. It was hooked up to an existing boiler and also came with a 50 plate hx as well.  Not sure witch one will be better. Local dealer said he prefers sidearm due to water quality in the area.  Is a 50 plate too much for dhw?