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DHW lukewarm from sidearm heat exchanger

Started by Karladams, February 08, 2019, 02:10:17 AM

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Karladams

Hey everyone, new to the forums and looking for help/advice.

I've recently purchased a sidearm heat exchanger and installed it onto a brand new hot water tank. This is my second crack at a different install but I'm still only getting lukewarm water. 

My current install is as follows. I've got a T coming off the DHW tank drain, straight up into the sidearm. The sidearm goes straight up to the top of the DHW tank with a 90 degree straight over into the anode port (anode removed). The pipe is only 2.5 inches higher than the top of the tank. The OWB HOT is plumbed into the top of the side arm and the return at the bottom. My OWB says my water temp is 184F although I don't know what it is at the sidearm. The sidearm is incredibly hot to the touch but yet the DHW is hardly lukewarm. 

My original install was a bit different. Had a T coming off the drain, with a 1.5 inch drop ( hot water tank is up on blocks to get this drop in the pipe) then went over about 7 inches and then up into the sidearm. The top of the sidearm was plumbed into the PRV port on the side of the tank. OWB hot was at the bottom of sidearm with return at the top. This setup also barely got lukewarm. 

With either of these setups I thought things would work but I am unable to get any hot water. I can post pictures of my current setup later if needed. Does anyone have any advice?? At this point, I would like to try and avoid installing a plate heat exchanger. I would like to get this sidearm working. So many people seem to have great luck with them 

albirk

Stove water (hot) in the bottom and return out the top. You will need a bleeder valve on the 90 at the top to let the air out of the sidearm going to the water heater. If you have a mixer valve it might be that also.

ButchC

You woulnt happen to have the inlet and outlet of the water heater switched would you? Dont feel alone with SA issues. I messed around with my sidearm for 3 months and never did get it to heat enough water to keep the wife happy. Another issue with them is the way the heaters are designed. Make up water goes to the bottom and thats where the sensor is to turn the heater on. As soon as we opened a tap the heater came on anyway. I ended up adding a plate exchanger and fixed the supply issues but left the side arm as I owned it. Now we have the best of both methods,  plate supplies endless hot water and the sidearm keeps the tank hot when there is no usage.  I know that others have made a side arm work but neither I nor my dealer could make ours work to our satisfaction.
Peterson JP swing mill
Morbark chipper
Shop built firewood processor
Case W11B
Many chainsaws, axes, hatchets,mauls,
Antique tractors and engines, machine shop,wife, dog,,,,,that's about it.

Karladams

Okay so this is where I'm at this morning. After having the setup running for 17 hours my hot water is at about 90F, drained from PRV and checked with thermometer, whereas cold water form the tap is about 48F. So up a bit but not the 160F that people say it should acheive in 3-4 hours. 

The cold water inlet and hot water outlet are clearly marked on the hotter tank so having them mixed up shouldn't be an issue. 

I do have a bleed valve at the top of the sidearm so and air trap also should be an issue



 

  

straincm

I would check out your mixer valve, open it up to the hottest and make sure you have it plumbed in correctly. Also, can you check the water temperature at your bleed valve? 

albirk

Your hot from the boiler still need to go to the bottom of the side arm to help pull the cold water off the bottom of the water heater to make the percolator affect work. I do not have a mixer valve on mine I mix with a ball valve between the hot and cold lines and can get 190 degree water at the facet if I close the ball valve. Is the copper line from the elbow to the center of the water heater hot hot or just warm if it is just warm you have air trapped. 

mike_belben

What he said.  Run your hot to the bottom.  You need to create a thermal siphon for the full length of the side arm to be conducting thermal gain. 
Praise The Lord

boilerman101

I'm also on board with putting your OWF water in low side out higher side port of exchanger to maximize thermocycle. Also be sure to purge air pocket out of the domestic line coming across top of the water heater. Literally hook a hose to that drain valve on the end and run a gallon of water into a bucket or sump pump to make sure you have all the air out of the domestic side of the exchanger at the highest point. Also confirm tht the mixing valve is set or working correctly. I never run out of hot water with just a 40 gallon water heater with electric element turned off using a side arm exchanger like yours.

woody_88

 

 

 Hi all, new to the forum and was looking for a way to get my feet wet. I'm with the previous poster's on how to hook up.

Couple months back I had a new OWB installed with hot water side arm. It works so-so, only thing it fails at is filling the bathtub before running cold. Might need to do a full on air bleed like suggested above. I've attached a couple photos of my setup for reference. T out the bottom, also where water entry into the system is (see sprayer), and then straight up and over top thru the anode port

snowstorm

i have a 007 taco pump on mine at the manifold from there to the water heater is 50 ft. when i first build a fire i turn the pump on for 20 mins. the rest of the winter its off . and the water is really to hot. i teed into the outlet on the heater as close to the heater as you can. if its to high it will not work as well

mike_belben

I used a sidearm sort of thermal loop on my home made woodstove rig at my last house.  It required a gate valve on bottom so that the expanding water could not be forced back into the draincock.  You want the hot water to go up and push the cold water down for a constant loop of circulation. 
Praise The Lord

ButchC

Quote from: Karladams on February 08, 2019, 12:26:43 PM
So up a bit but not the 160F that people say it should acheive in 3-4 hours.

The cold water inlet and hot water outlet are clearly marked on the hotter tank so having them mixed up shouldn't be an issue.


Ya, switching the inlet and outlets shoulnt be an issue but I just fixed a owner installation last week with that issue and owner had similar complaint.

If you can get a side arm to take a cold tank to 160 in 3-4 hours please post how you acomplished it. When we were fooling around with my sidearm we reversed the loop flow and  could not tell any differance in how well it heated the domestic side. I see no reason that your install should not heat water as good as any side arm will. Is it possible that something is blocking the domestic tube?
Peterson JP swing mill
Morbark chipper
Shop built firewood processor
Case W11B
Many chainsaws, axes, hatchets,mauls,
Antique tractors and engines, machine shop,wife, dog,,,,,that's about it.

woody_88

That's a good point from ButchC, maybe try running a piece of 1/4-3/8" wire round stock stuff from the home store down it. My installer added shutoff valves to do this periodically because of my hard water. 

woody_88

Oh and to add, the second install the OP did with the hot entry on the bottom and sidearm straight into (assuming straight) the PRV is how I wish mine was installed (will be one day.) this eliminates any chance of a thermal block from what I understand.

How that setup only gave lukewarm water is strange, I can see how the current 2.5" above the top would not work as well. Even with mine darn near touching the top, I can feel the water cooling down as it travels from the sidearm(by the air valve) to the entry into the tank. Takes a lot longer I believe because of the thermal block it has to overcome. 

straincm

Another thought. Water needs to flow from boiler to side arm, then any other heat draw after the side arm. You need the greatest delta T possible to get as much thermosiphon as possible. I don't know if this is the case or not, just something to check.

Outlaw

I'm in the same boat with not getting the side arm working.  Got tired of messing with it and installed a potable pump to circulate and never looked back.   
TK 1600, old logging equipment,  sthil chainsaws

woody_88

Where did you install the pump? Any info on the pump?

Outlaw

I had enough room above the side arm to sneak it in. The pump is a taco 006-b4   
TK 1600, old logging equipment,  sthil chainsaws

overclocking

Quote from: Karladams on February 08, 2019, 12:26:43 PM
Okay so this is where I'm at this morning. After having the setup running for 17 hours my hot water is at about 90F, drained from PRV and checked with thermometer, whereas cold water form the tap is about 48F. So up a bit but not the 160F that people say it should acheive in 3-4 hours.

The cold water inlet and hot water outlet are clearly marked on the hotter tank so having them mixed up shouldn't be an issue.

I do have a bleed valve at the top of the sidearm so and air trap also should be an issue



 

  
Your hot water needs to enter the bottom of the exchanger and heat that water first causing it to rise.  It will work either way, but the proper way is to excite the colder water at the bottom first. What temp is the water on the boiler side?

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