Sidearm help

[Dairyman]

 

 

Ever since I installed my sidearm I haven't been able to flip the breaker off to my elec dwh like many on here have been able to do. It definitely does aid in heating the water but I can still hear the elements kick on when hot water is used so clearly the sidearm is not keeping the entire tank hot. Could the problem be the height I have it mounted?  The bottom of sidearm is about even with bottom thermostat/ element so I'm thinking of re piping it lower to try to keep that thermostat surrounded by owb heated water.  Anything else I might be missing here? 

 

[beenthere]

What is the temp of the sidearm water relative to the temp setting of the dhw heater? 

Why not turn the power off on the dhw heater and just go with the hot water from your boiler? 

[Dairyman]

The temp of the water at the top of the tank is usually 130-150 degrees. Thermostats are set at 120. But as soon as we use hot water such as a load of laundry or shower, enough hot water is used that the bottom element is below 120 again.  Once tried turning that element off but that left us with less hot water than is even needed for a load of laundry.  What I'm trying to explain is that it seems like my sidearm is only heating the top half to two thirds of my tank. 

[barbender]

Have you drained the sediment lately?

[Gary_C]

Some questions.

How big is your water heater? Mine is an 80 gallon but yours looks smaller.

Does your feed from the outside boiler enter the lower connection? What is the temperature of the incoming water?

On mine the top water connection from the sidearm heater to the water heater goes into the relief valve connection. The relief valve is on the other side of the tee connection to the water heater. The top line from the sidearm should rise to a right angle air eliminator and then go horizontally to the relief valve tee and into the water heater. Never go up and then back down like yours does. It's OK for the bottom feed to the sidearm to drop and then rise to the sidearm but never the top line from the sidearm to go up and back down to the water heater. You also have to have an air eliminator on the top of the sidearm to avoid air locks. 

My OWB is sending 180 degree hot water to the house and I also have a mixing valve on the hot water supply in the house and our hot water is still way too hot. We never run out of hot water.

[DDW_OR]

looks like the bottom of your side arm is correct

to top should connect to the pressure relief valve

here is how mine is hooked up
had to add an anti scald valve to reduce the hot water to 135 deg, was at 190 deg
135 to keep bad stuff from growing in the tank






 

[Dairyman]

 

 



 

My pic skills are mediocre at best but here are some slightly better pics of the top and where my sidearm goes into the (former) t&p valve port, unlike some of you that had that on the side.  The horizontal pipe that goes back into water heater is 3" above the top of the unit (pics mb make it look higher). Would shortening that stub pipe by an inch or two really make any difference? Also Gary mentioned an air eliminator at the very top 90° (or in my case the T where the t&p valve is) . I've cracked my t&p valve and only gotten water, no air.  But if there's another piece that's supposed to be on there I'd like to do it right.  This is an 80 gal unit and only 2 of us in the house.  The anti scald valve is set right now at about 115. I know the water that comes out of t&p valve is 130-150 or higher depending where my owb is set at but I've just never been able to achieve the endless hot water I've read so much about! 

[DDW_OR]

OWF hot water into the bottom of the arm


the Green is the thermopex pipe
black arrows are OWF water flow, pumped

Blue are water heater thermo convection flow, no pump


 

[Gary_C]

That ball valve just above the sidearm should be open and it looks like it's closed in your picture.

I would be surprised (but not completely shocked) if there was not a side opening high up on your water heater. The way yours is plumbed should work but somewhat limit the hot water flow to the tank. Remember that flow thru the sidearm is weak and only induced by the difference in density of increasingly hot water as it rises.

Yes, I have an Automatic air eliminator at the top of the flow up from my sidearm. It is a Watts and is important because as you heat water air bubbles form and if the air collects at the top of the piping it can cause an air lock which can slow or stop the gravity flow. 

[ButchC]

I had a very similar experience, I couldn't make a side arm work to my satisfaction and I had to get into what's going on inside to figure it out. Contrary to popular belief the water in a water heater is not the same top to bottom, it is layered.  There is a dip tube that takes the incoming cold water to the bottom where a sensor sees the drop in temp and turns on the heater. The hot water rises as it is used and there is a relatively narrow cold to hot area in the tank that rises when the elements cant keep up with demand. This knowledge is important when trying to figure out whats going on when things  are not working.

 Let me say that we use a LOT of hot water, probably 2x the average home. My experience was same as yours, water at the tap was hot, boiler loop hot, side arm circulating but as soon as a hot water was used the water heater would kick on. Now I know why that is but we didn't spend $XX to still be burning gas so next move was to turn the burner off.  Obviously people are getting by that way but with 3 kids and clean freak wife the side arm couldn't keep up, two showers and water was cooling off rapidly. 3 trips by 2 dealers and 1 plumber all said the side arm is working as it should, nothing can improve it.  Since we already had it I left it in place and uminstalled a plate exchanger. Now we have the best of both types, endless hot water from the plate and the side arm keeps the tank hot during periods of no usage. Just my experiances

[Gary_C]

I should add one more comment. 

I am not sure why there are two inline ball valves, one above and one below the sidearm in your pictures. That is redundant and possibly dangerous to have two shutoffs on one length of pipe without a relief valve in that section of pipe, especially with it being a length of pipe thru a heat exchanger. I also noted before that the valve above the sidearm was closed but now I see the one below is also closed. That makes doubly sure the heat exchanger will not work with both closed and dangerous too.

[DDW_OR]

open this valve



 

[Gary_C]

open this valve

The problem is there are actually four ball valves on the two flows of that sidearm. If you look at the first two pictures the OP posted there is another valve at the bottom of that sidearm and that is both redundant and dangerous and they are both closed. The way the setup is pictured, the domestic water side is blocked at both ends of the exchanger and if you are feeding 180 degree hot water to the water jacket of that sidearm you could build up enough pressure to rupture the hot water pipe internally in the sidearm.  

[beenthere]

My experience with a sidearm ahead of the domestic gas hot water heater is a 30 gal stainless steel tank with a copper coil within the tank. Worked for 40 years until I removed the inside wood fired boiler last year. Gravity flow of hot water from the boiler in at the top and out at the bottom. Rarely would need to burp the air from the bleeder at the top to get flow to start again on its own. Domestic cold water would flow through the 30 gal sidearm on its way to the dhw heater. 


 

[Dairyman]

I should have mentioned in my op that I have NOT fired up for the season yet and these pics were taken when I made my op. The 2 valves in question are closed during the off season mainly to avoid having hot water flowing out from the insulated tank into the uninsulated sidearm. Probably a very minimal loss of heat but since they are there, I close them. I also run my circulator pump in the off season occasionally and this keeps from heating the boiler loop water with my dwh. I would never leave them closed with the owb running.  The original reason for installing the 4 ball valves is to be able to isolate the sidearm should I ever have problems and make it easier to repair, clean etc. One of the recommendations I read on this forum and others when doing my original install was you can never have enough valves, even if you think you'll never use them. And yes,  the green arrows in DDW's pic shows the direction of flow how i have it- in the bottom and out the top. So given that those valves are always open during heating season I don't feel like they are part of my problem,  are they? Hopefully this clears things up a bit. 

[beenthere]

Dairyman
Do you know if your water in the sidearm is circulating by gravity when those valves are open and you are pumping/circulating hot water from the wood boiler through the sidearm? The temp of the boiler water should be close to the same coming out the top and back into your dhw tank. i.e. too hot to touch if 180°.

If that isn't the case, then you may have to add a circulating pump to move that water through the sidearm. 

[barbender]

Does your hot water loop from your OWB circulate continuously, or on demand?

[DDW_OR]

.........If that isn't the case, then you may have to add a circulating pump to move that water through the sidearm.

move valve 1 to top pipe
this way you can close it, then open 2 to get the DHW flowing in the correct direction
then close 2
then open 1
or install a mini pump at the top pipe.
also insulate all pipes that have any heat.


 

[Gary_C]

move valve 1 to top pipe
this way you can close it

Sorry but that would probably be a code violation to put a shut off valve between the tank and the relief valve (valve 2 is the relief valve). Also, those relief valves tend to malfunction if used to vent repeatedly. They are normally made to vent once and then be replaced.

Dairyman, the best circulation flow by gravity would be if you pipe the top pipe from the sidearm either directly into the tank or even with a horizontal pipe that then enters the tank in the upper side. Going up over the top and then back down is going to impede the flow especially if air accumulates in the top of that line. It's hard to say how much it will impede or stop the flow because every installation is a little different. All I can say for sure is mine is piped into a side opening and we have seriously hot water that we have to warn visitors about even with a tempering valve. We never run out of hot water when the OWB is running.