Side arm vs plate heat exchanger for domestic hot water?

[Slick]

I see most guys on here using plate heat exchangers...my central boiler dealer seems to prefer side arm exhangers for domestic hot water....what are the pro's and cons to each for domestic hot water?

 

[bassman]

side arm - slow
plate - fast

search this and there is alot of discussion about it and all the ways of doing it.

 

[tanker]

I,ve got a sidearm on a 50 gallon wh,2 teenagers still at home and never run out of hot water.That is,was my preference because cheaper and I live where water is very hard and would most likely plug a hx over time

 

[Blazin]

Yep..the plate exchangers will plug pretty quick with hard water and should be cleaned yearly. The sidearms are'nt really effected by the hard water nearly at all. Plates do make faster heat but require a pump to circulate the water, where the sidearm works on convection and no pump is needed.
I have a 40gal hotwater tank with a sidearm and have never ran out of hot water either.

 

[motoman3b]

Side arm was the way I had to go because of hard water but be sure to hook it up with unions so it can be removed to clean... had to clean mine after one year because settlement blocked the bottom of it!

 

[oneoldbanjo]

I have installed both a Plate Exchanger and a sidearm - I didn't know which to use so I installed both. As it turns out this is waaaay overkill.

Plate Exchanger - This works instantly in heating my water as it enters the water heater and supplies all the hot water I ever need. I shut the heating elements off in my water heater and unless we are gone for days - the normal use is enough to keep hot water entering the water heater and we never run out of hot water. When we were gone from Thursday morning until Sunday night over the Thanksgiving weekend we returned to lukewarm water in the water heater. (I had the sidearm turned off as we were trying to extend the burn in the OWB as long as possible).

Sidearm - This works really well for keeping the water warm once it has entered the water heater. If you are using a lot of water over a short period of time it will probably not keep up, and it may be necessary to keep your water heater set at a temperature that will come on once you start using water faster than the sidearm can heat it. I have installed mine with a valve that I can shut off the flow from the water heater and prevent the thermosiphon from occurring. I did this as with the plate exchanger and the sidearm in operation our water gets very very hot, and when I am away and the OWB goes out I don't want the water heater providing energy to the OWB when the fire goes out - and in the summer I don't want some kind of thermosiphon going on with the running water heater and the out of service OWB.

I really don't think you need both of them as I installed - and choosing between the two I would probably use the Plate Exchanger. I will have to wait and see how long the hard water will take to plug up our exchanger, we have a hardness of 10 grains on our public water.

Blazin:

An extra pump is not required for a Heat Exchanger in my system. The domestic water coming into the water heater passes through the heat exchanger just before it goes into the water heater inlet - the force needed to push the water through the heat exchanger is the pressure on the water service line. The water from the OWB is pushed through the heat exchanger by the pump that brings the hot water into the house for the furnace, and it runs 24.7.

 

[Butch(OH)]

The guys have pretty well nailed it. Disadvantage of the side arm is capacity, disadvantage of the plate is you have to keep the tank warm when not using any hot water. Side arm wouldn't make enough hot water for 5 of us and I added a plate to the loop this past summer but kept the side arm in the loop since I already owned it. The water heater is now shut off but we have a lot of money in both plus all the valves and unions.
My opinion is 1-3 go with a side arm, more than that go with a plate. Hour long showers and clean freak wives will change those numbers

 

[Slick]

Thanks guys and yep it sounds like I had the pro's and con's pretty much right in my head, you guys all just reinforced them I like the concept of the plate better but I don't think I'll circulate enough water to keep the tank warm with one..I'm single with girlfriend that's over alot so could call it a 1.5 person house...I'm thinking the sidearm is better as the tank will always be hot waiting for us, doubt we'll drain that tank and need more hot water to often.

 

[motoman3b]

Thanks guys and yep it sounds like I had the pro's and con's pretty much right in my head, you guys all just reinforced them I like the concept of the plate better but I don't think I'll circulate enough water to keep the tank warm with one..I'm single with girlfriend that's over alot so could call it a 1.5 person house...I'm thinking the sidearm is better as the tank will always be hot waiting for us, doubt we'll drain that tank and need more hot water to often.

One other thing I did to my sidearm heat exchanger was insulate it with some foil type bubble wrap and some pipe insulation. Dont know as this was really necessary but helps reduce water temp drain due to coolness of the basement

 

[oneoldbanjo]

I insulated my sidearm and all the piping in the basement. The heat coming off the pipes was letting too much heat into the basement. I used the foam insulation with the adhesive on the seam and used the 1" stuff for all the piping, and I just stuck two of them together to cover the 2" pipe on the sidearm.

 

[Slick]

Everyone using a mixing valve ontop of the water heater with their side arm? Anyone have a good diagram of hooking a side arm up? Central Boiler's are pretty good looking but I see several variations, thoughtI'd ask around.

 

[Blazin]

Mines hooked up between the blow off on top and the drain on the bottom. I failed to note that I built my own it's a 2" outer pipe with the 3/4 running thru it 32" long and it has never run out of heat even after 3 loads of laundry and 2 showers before mine. I put a tempering valve in, but my hard water put the cabashe on that after a year. Just gotta remember to get the water temp dialed before you jump in the shower, as not to burn the :censored: out of you! I covered all my lines/pipes with the foam rap insulation....

 

[Slick]

That brings up a good point I was also thinking of....who else has made their own side arm? Doesn't look like there is much to it...and at $100-140+ bucks I'm seeing them go for...looks like an inner and outer pipe and some T's soldered together?

 

[oneoldbanjo]

The equipment list is basically a 5 foot length of 1" ID copper pipe, a 4 foot length of 2" ID copper pipe - and then two 2x1x1 tees. The only weird thing about the tees is that the 1" sides allow the pipe to slide completely through and don't have stops - and the 1" should be inline with the 2" so the pipe is centered in the 2" outer pipe. It takes a bit of heat to solder the 2" fittings but can be done with a good propane torch. You will then need to get the adapters to connect the PEX tubing to the heat exchanger and the copper and brass fittings to connect to the water heater. If you have the lines to the water heater go above the heater and connect to the top of the water heater you will need an air release valve to let any trapped air out.

 

[Butch(OH)]

That brings up a good point I was also thinking of....who else has made their own side arm? Doesn't look like there is much to it...and at $100-140+ bucks I'm seeing them go for...looks like an inner and outer pipe and some T's soldered together?

Ya better go price some copper tubing and fittings. The end fittings are special but available. When I priced it out I just bought one complete.

 

[Slick]

Thanks, that's basically what I thought. The T's are what had me concerned...are you saying the 2-1-1 T does let the 1" inner pipe slide through it with no stop? I was afraid it had a stop and the inner pipe wouldn't slide though...wasn't sure how I was going to handle that...did you guys just manually open up the stop in the T to allow the inner pipe to slide through?

 

[Slick]

Yeah good point Butch, I was pricing fittings as this thread has progressed and it's a bit cheaper to build it but it's close enought in price to almost just buy one and save the time...

 

[Slick]

Side arm shopping...anyone seen or used a short one like this
http://cgi.ebay.com/Side-Arm-Heat-Exchanger-Outdoor-Furnace-Boiler-Stove_W0QQitemZ200287401338QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item200287401338&_trksid=p3911.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

I like the concept of more surface area inside the tube...seems really small though I'm thinking it would mount in the middle of the tank vertically with a nice 45degree up and out of the exchanger back into the tank...might help with thermosiphoning instead of having to go horizontal like with a long exchanger.

I only started thinking about this one as I need to get a water to air exchanger and have used this ebay seller before...might get them at the same time.

 

[Jkebxjunke]

Side arm shopping...anyone seen or used a short one like this
http://cgi.ebay.com/Side-Arm-Heat-Exchanger-Outdoor-Furnace-Boiler-Stove_W0QQitemZ200287401338QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item200287401338&_trksid=p3911.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

I like the concept of more surface area inside the tube...seems really small though I'm thinking it would mount in the middle of the tank vertically with a nice 45degree up and out of the exchanger back into the tank...might help with thermosiphoning instead of having to go horizontal like with a long exchanger.

I only started thinking about this one as I need to get a water to air exchanger and have used this ebay seller before...might get them at the same time.

I bought 2 of those.. ( one for each of my houses..) I havnt installed them yet.. they look well made
I am thinking that in my main house where its me, wife and 2 kids... I my use a FP on the incoming water to the DWH and the side arm to maintain the temp... now for the other house where it is just my dad... I may just use the side arm... as for the seller.. they seem to be great people to work with.

 

[rx7145]

Side arm shopping...anyone seen or used a short one like this
http://cgi.ebay.com/Side-Arm-Heat-Exchanger-Outdoor-Furnace-Boiler-Stove_W0QQitemZ200287401338QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item200287401338&_trksid=p3911.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

I like the concept of more surface area inside the tube...seems really small though I'm thinking it would mount in the middle of the tank vertically with a nice 45degree up and out of the exchanger back into the tank...might help with thermosiphoning instead of having to go horizontal like with a long exchanger.

I only started thinking about this one as I need to get a water to air exchanger and have used this ebay seller before...might get them at the same time.

Looks like it should work good.