Is my side arm installed correctly?

[top_prop]

Newbie here... think I've got a bad contractor problem...

I Contacted a wood boiler company, and got the information of a local pro from them... he installed a wood boiler,  new hot water heater  (76gallon propane), side arm heat exchanger and put a heat exchanger in my forced air system (installed Sept 2020).   Its wasn't cold enough to bother firing it up until recently when lows were approaching below zero (no antifreeze so I fired it to protect it).

Hot water heater (DHW) output got a tempering valve that he said was set to 120degF by the factory.  Because the boiler was going to heat the water way to hot to use (I get this is a good idea.... even code in most areas).   However The only temperature reading in the system I can get is via logging into the OWB.

I've noticed the propane hot water heater blower kicking on quite often even with the boiler saying the water it is suppling is 165-185 deg F.... even when I don't have anyone showering...  its common usage like washing hands, doing a load of dishes, or using the high efficiency washer, or even nothing at all, that turn the propane heater on.

He put a bleeder at the top of an 8" loop above the SideARM that feeds the DHW tank.   I've bled it and it immediately shoots out water.  so I don't think it is air locked.

After doing some cursory research I suspect I'm getting very little recovery because his design has made a thermal lock (the 8" tall loop).... also he fed the hot water from the boiler into the bottom of the side arm (all the instructions I found said to put it at the top and return water was to come out of the bottom.    

I contacted him and he told me there is nothing wrong with the installation.   As if we are using too much water too fast... or the new propane heater is malfunctioning.  he directed I turn it to vacation/pilot...   I believe he's trying to show that it is indeed heating (which it will... just poorly with much slower recovery than without a thermal trap).

I had the hotwater heater's thermo stat on A (of A B C with C as the hottest), so I turned it to Vacation (the absolute lowest setting of the hot water heater's T stat).



I circled what I think is the thermal trap above.



 
Showing feed of hot water into bottom of side arm (which is opposite of instructions i located online).


Am I right to be concerned?


What would you do?

Does it look like I'm being robbed of performance due to a poor install?

Is it a big deal to feed the hot from the boiler into the bottom of the side arm?

Thank you in advance for your help!

A Newbie..

[mike_belben]

Is this system using circulator pumps to move the water or thermal siphon?  

[brianJ]

Always thought the correct question was, "Is my side arm holstered properly?"

[top_prop]

Is this system using circulator pumps to move the water or thermal siphon?  

The DHW is thermosyphon (no circulator).  
The hot water from the  (OWB) boiler is of course always circulated through the side arm heat exchanger by a taco pump at the boiler

[albirk]

The pex lines are correct hot in the bottom return out the top to go to your coil in the lower fitting and return to the stove out of the top fitting. The 8" loop out the top of the sidearm looks like the problem to me.

[47sawdust]

My personal experience has shown a circulator in the system will get you more more hot water than a thermosyphon.

[mike_belben]

Its the inrush of cold ground water that makes your flame fire up.  Preheating here is key. 



To fix the jacked up thermalsiphon,  put a tee in the hot water outlet riser pipe above the water heater and run the sidearm up to it. This will circulate the full tank prpoperly but its point is to raise the temp.up quite high.  The mixing valve might be defeating that depending on how its plumbed.  And also i had a gate valve at the bottom to prevent reversal.  You want cold coming out the bottom only. Never hot going in the bottom.  



Back to preheating... I suggest you look for a used Superstor to park next to your existing water heater.  Its a 2 chamber, 4 port tank in sizes from about 20G to about 100g, that is usually used as a DHWHeater when running a boiler.  Really just a monster sidearm in tank form with a heating coil inside.  


If you run your cold water line [from the well or street] through it as a preheater before sending it to your propane water heater inlet port, the propane devices thermostat will not see cold water until you exhaust the superstor, thus it wont kick on.   I would route boiler water into the sidearm first then out of the sidearm to the superstor then back to the boiler.


  A lot of folks run 4 port flat plate heat exchangers [fphe's] but they dont perform like a superstor.  It takes TIME to transfer heat and FPHEs are an on demand sort of thing, they have to be huge to transfer much heat in a short time because youre only starting with say 180* from the boiler.  Not a 900*f  propane fire like these tiny new on demand tankless units. They work because delta T is massive so btu transfer is fast.  With low delta T you want larger volumes of liquid to give more time.  That sidearm for instance wont make a good preheater because within a few minutes itll be stone cold.  My preheater held 10 gallons of 180-212f water and would drop to icewater in one shower then need an hour to recover.  So preheating is about volume.  Sidearms work great but only for temp increase of parked storage water over time. 



My homemade wood assisted water heating system years back had no mixing valve.  Well.. In my opinion every faucet in the house is a mixing valve, the user just needs to know not to scald themselves with straight hot water [toddlers being the exception.]  170F works magic in the dishwasher and on my work pants (with straight Dawn ultra to boot!)



If you want 40 minute showers from a 20gal water tank it wont be possible with a mixing valve but it is if you raise the temp to store more BTU. if you bump the storage temp of your 40gal tank up say 30 degrees or so, now itll last like an 80gal with a valve because the 40 gal is storing a comparable quantity of btu.  Just open the cold faucet more and hot less. 



 If you were preheating the ground water AND had a 180F storage temp all from the wood fire, youd never kick the gas on and never run out of very hot water.  This is what i did using a sidearm and a ground line preheater coil submerged in an insulated tank ontop the woodstove. My gas only came on if i hadnt ran stove in day or two. Scalding hot showers for an hour if you want. 

[Gary_C]

What you are calling a thermal trap is actually an air eliminator that is supposed to be in the line right where it is. The problem with your installation is the 8" loop at the top of the sidearm is restricting the siphon action. 

It looks to me like the contractor had a height problem and created that 8" loop above the return port on the water heater. On my similar installation the contractor simply moved the sidearm to the side further and put the shutoff valve in a horizonal line that feeds into the hot water heater.

My sidearm works well but I do have an 80 gallon hot water heater and we never run out of hot water. In fact when the woodstove is running it is hard to temper the water temp down to safe levels. 

[top_prop]

What you are calling a thermal trap is actually an air eliminator that is supposed to be in the line right where it is. The problem with your installation is the 8" loop at the top of the sidearm is restricting the siphon action.

It looks to me like the contractor had a height problem and created that 8" loop above the return port on the water heater. On my similar installation the contractor simply moved the sidearm to the side further and put the shutoff valve in a horizonal line that feeds into the hot water heater.

My sidearm works well but I do have an 80 gallon hot water heater and we never run out of hot water. In fact when the woodstove is running it is hard to temper the water temp down to safe levels.

Thanks for your help.

I understand that the bleeder is there to bleed air.    I confirmed no air lock by opening it and seeing instant water flow.    I believe the entire 8" vertical loop acts as a thermal lock...  

I was there... the contractor did have a height problem, but one  that he failed to plan for... he came straight out of the bottom hole of the hot water heater and sat the side arm on it...    His mistake was starting at the bottom and working up.  

He should have started with a horizontal T at the top hole and put the bleeder level there then built down...  when he got to the lower hole he would have constructed a  loop to get up to the lower hole in the hot water heater where he could have T'd in the drain valve...   a loop at the bottom is beneficial from what I've read:  it lets the cold water settle there then rise  right through the side arm and out.

Had I known better then, I would have intervened.


Edit to add:  he complained about the hotwater heater the entire time...  I think it was a little different lay out than what he was used to... he kept mentioning that it was bigger than he'd seen in anyone's home but he'd make it work...

Tom, the newbie

[top_prop]

For those who care to follow my saga:

So after my wife took a shower that she couldn't get hot enough to her satisfaction (remember I put it on vacation per the Pro's direction... took 24 hrs but the water at the faucet is no longer "HOT" to the touch), I texted the Pro and asked when he was coming over to look at it like he promised (he told me to put it on vacation/pilot and he'd be over in a day).

He asked if we ran out of hot water... (thinking we wouldn't).  Of course we had...   he still maintains there is nothing wrong with the install, and said he even sent my picture of the install to the boiler manufacturer and they are backing him that there is nothing wrong...

I asked why it couldn't seem to make enough hot water without Propane backing it up...  he said the tank was too big!   I told him that if anything, too big a tank would be filled with too hot of water that his tempering valve would mix with cold and we'd have a bunch of hot water...  not less hotwater

He said the problem is that I bought the more expensive gasification model that lets the water temp vary from 185-165 as set by default.. and I should set it to keep the water at 185-175...  like the older standard model did...   I told him right now according to the web interface: its taking about 10 to 12 hrs for the water to cool from 185-165....   and even at 165 degrees if the thermosyphon was working correctly, I should have a full tank of 145 plus degree water (with a 20 degree delta T to get heat flow)... not a tank full of less than 120 degree water (judging by my wife's less than hot shower)...   And if it was pulling heat out of the boiler efficiently it would probably be pulling the boiler's water temp down faster... but if the heat isn't flowing, the boiler water will take longer too cool...

He said he didn't agree, but said he wanted happy clients and would re-plumb it however I wanted, but wouldn't warranty the install if I had him change it.... and he is convinced that it is fine.

Which I asked:  If so, why am I not getting a tank of hot water out of it?   Why do the instructions say to put loops at the bottom to avoid a thermal lock?

As our deer season is about to open up, and I know he hunts I asked him to come fix it after he filled his freezer.  We'll see.

Another thing that I realized is that there could be internal blockages slowing flow/syphoning...  how do you check for that?  

[mike_belben]

Drop this guy.  Get a map gas torch, some solder, flux, tight space cutter, sandpaper.. Watch some technique vids on youtube, practice on scrap a few times and use a bread ball to stop drips while you sweat joints. Yes, pack a piece of white bread in the pipe thats continually dripping, the drips will ruin your solder.  The bread will disolve and wash right out no issue.  Quench your joints with a wet rag before putting strain on them. And ALWAYS plan for the joint to fail and need to be cut out and redone.. Leave yourself trim and buy contractor 10 packs of fittings not just what you need. 


Like i said, gate style check valve on the bottom so cold water comes out of the tank.  Chop that loop off, toss the air bleed junk and run straight up to a tee in your top outlet pipe. Try to put a very slight pitch in any horizontal section so that air moves up to the faucets and farts out.  This is an hour job or less and i wish i was there to just bang it out for you.

180 boiler loop should get you 160ish water tank by evening. Your bathroom should be a big fog box and wife should be stepping out with a sunburn and a smile.  


Your plumber is just talkin silly.  People with boiler based hot water dont have propane backing it up. And they have endless scalding water, my wifes house had it.

[mike_belben]

By the way..my home made woodfired thermal siphon routinely melted the foam insulation off the top pipes, ive probably got pics somewhere in my old phone.  

This guy making dont-expect-much excuses is pithing me off.  

[E Yoder]

As was mentioned, the loop is a problem, it's trapping and stopping flow. It needs to be replumbed.
FYI, I have used nearly a thousand flat plate heat exchangers preheating the water going in the water heater, and NONE run out of hot water. Flat plate heat exchangers work awesome.

[mrcaptainbob]

Before tangling with getting the instller to modify the sytem and cancel warranty, insulate the side arm. I had the same issue. I installed the system myself and was surprised there was barely warm water. Had the temp control valve on the water heater and at first suspected that. But the outside of the side arm heat exchanger was VERY hot. Wrapped it with that foam insulation and it made a HUGE difference! Did that on both water heaters and am very pleased now. It's a cheap experiment that I would suggest trying first.

[mike_belben]

FYI, I have used nearly a thousand flat plate heat exchangers preheating the water going in the water heater, and NONE run out of hot water. Flat plate heat exchangers work awesome.

What are you doing with a thousand FPHEs?  
I did not get very good results out of a 30 plate [iirc] in the beginning and switched to a copper coil submerged in about 10 gallons of stovetop water. That worked well once up to temp.

[top_prop]

Before tangling with getting the instller to modify the sytem and cancel warranty, insulate the side arm. I had the same issue. I installed the system myself and was surprised there was barely warm water. Had the temp control valve on the water heater and at first suspected that. But the outside of the side arm heat exchanger was VERY hot. Wrapped it with that foam insulation and it made a HUGE difference! Did that on both water heaters and am very pleased now. It's a cheap experiment that I would suggest trying first.

Thanks for a good idea.

Before I took the pictures I had a bunch of pipe insulation on stuff.   I took it off (and set some of it on the hot water heater) to take the pictures.   The pro however didn't insulate a single thing.    Before I put on the insulation with tape and made it more permanent: I'm hoping to get it fixed  (ie no thermal trap at the top).   

I want the Pro to own this install, fix it,  and warranty it.   I want him to learn that he's been cutting corners (as he's claimed he has hundreds in the area like this) and should take a minute to think through how he can make it the best he can for his customers.   He's a nice guy that I like outside of cutting corners on my project... I hope to help him improve by improving my install.   He's also plugged in and well respected in the community I just moved to for my retirement.

Yours,

Top_prop the newbie to OWB's

[albirk]

If that drop was on the bottom of the water heater it would work fine. I have installed around 200 of them and I learned from mistakes. The drop needs to be on the bottom and level on the top. I have set the water heater up on a platform so I could get a larger drop on the bottom and you will need the bleeder valve in the 90 to get the air out of the system. If you need more help just ask.   

[E Yoder]

FYI, I have used nearly a thousand flat plate heat exchangers preheating the water going in the water heater, and NONE run out of hot water. Flat plate heat exchangers work awesome.

What are you doing with a thousand FPHEs?  
I did not get very good results out of a 30 plate [iirc] in the beginning and switched to a copper coil submerged in about 10 gallons of stovetop water. That worked well once up to temp.

I install wood boilers for a living. Not saying other methods don't work. But I've found flat plates to be very simple and reliable. 

[mike_belben]

Glad to have your input.  What size do you prefer for a preheater application.. Port size and stack count. ?

[top_prop]

The pro sent his installer to my house yesterday.   Long story short is the installer replumbed it with the shut off valve and loop at the bottom.    Within a few hours we had good hot water.   I insulated it all this morning and we now have really hotwater with the Propane thermostat in vacation.

(I had tried to keep it simple before calling the Business owner & Installer 'the Pro'... I've always talked to the owner, but most of the work [everything except the trenching] was done by the installer).

The installer said he had always plumbed side arms out the drain valve but in the top of the tank  not a side port (ie he's always plumbe them back in where the hot water leaves).... and he knew those installs required him to keep the T no higher than 4" from the top of the tank... I pointed out the 8inch loop he plumbed in...   he felt the pipes and water, and admitted it wasn't hot enough and that I was helping him to learn something new.

It took some coaching but I got him to go straight out the top side hole of my tank with a T,  put the T&P on the horizontal 90 and then put the bleeder on top of the heat exchanger so it fed straight into the tank.  Then tie it all in to the drain hole with a loop down low.  He didn't like having to plumb the loop so low and close to the floor, and move the shutoff valve to the bottom: but he did it, and we got hot water.

After it was done and the water was heating: I mentioned the owner said that because I was having them fix this, he wouldn't warranty the installer's work.  I just got a very puzzled look and a head shake from the installer.  

I'm pretty sure the owner is deer hunting.   I'll endeavor to get him to clarify that they learned something here, should have done it this way from the start, and still own this installation.

Thanks for your help and advice!

A newbie

[E Yoder]

Glad to have your input.  What size do you prefer for a preheater application.. Port size and stack count. ?

I use a custom made 3x8" 30 plate with 1" outlets on boiler side, 3/4 on domestic. A 5x12 20 plate works well too, they usually have 1" on both.

[Dairyman]

If you haven't put all the insulation back on yet and it's not too much trouble would you mind posting pictures of it now that's it's done correctly? I'm preparing to do an install like this too and would be helpful to see what to do and what not to. 

[straincm]

On my sidearm I plumbed into the top of the tank, not into the side. All installation documents I found showed the same thing. Sounds like you have it working correctly now. 

[top_prop]

Well I though we had this licked...   I insulated it all back up (so I can't really give you good pics)...  I had the installer do it like in this video:  https://www.youtube.com/watch?v=9mkF5gI3bQo    only substantive difference is that he put a T in the top run out of the side arm with the T&P valve horizontal with the ground.   and put a shut off valve in the bottom loop so I can stop reverse thermal syphoning when I stop using the OWB in the summer (so it won't rob heat from the hot water as much when I'm just using propane to heat the water).

But after about 6-8hrs of us being in bed, when I get up in the AM I only have really warm water... not hot.

I think part of my problem is where the installer put the T stat of the heater...  I turned it from about midway between A and B and put it just above vacation...   I gave it a while to cool and such and we seemed good, but now after many days we never seemed to get really hot water again.    For instance I have to put the mixing valve on my shower to full hot, and I don't really get a satisfying hot shower, even in the morning when everyone has been asleep and not touching the water for 6-8 or even more hours.

I'm thinking I may need a circulator on the DWH side to speed up recovery.    The other suggestion here was to preheat the water before it hit the tank, but I'm short on space in the utility room (if I was to add a 40gallon DHW with some sort of heat exchanger I'd need more room)... and it just seems simpler and cheaper to try and put a small circulation pump in the DHW side of the side arm to decrease recovery time.

I'm also wondering if perhaps the heat exchanger is plugged on the DHW side...  how would I test that?

[mike_belben]

Use a temp gun to see what the in vs out temp is on each side.  I am gonna guess they should be near equal difference.  Meaning this side is leaving 20*f and that side is picking up 18 maybe.  That sorta thing.  


You said he put a valve in the bottom.  Did he put a check valve or a ball valve?   A check valve is full time automatic and is necessary to prevent a backward flowing thermal loop.