Help on plumbing for thermosiphon

I've worked on thoes bucket a day (baby boilers)too.I've also worked on gravity hot water heating systems.they were mostly 2 pipe systems(all the feeds to the radiators were tied together and the same with the returns.I HATED taking thoes systems out(HUGE PIPES).The feeds and returns were often 3" on the boiler.Boy I earned my money on thoes jobs.

The flo valves used in heating use the weight of the brass to stop flow.I think it may flow with swing checks if it's horizonal,but it would be slowed some.
Most poeple don't know this but if a circulator dies in the middle of the night you can open the flo valve to gravity around and get some heat.
I know you know this being a plumber.
DON

Don,
good point, those old gravity systems were a pain to work on, but you have to admit those old plumbers were pretty creative. I personall don't see the need for a check valve, my dads system has worked flawlessly for a many number of years. the only reason we put the pump on it was because the tapping for the hot in to the tank is about 10" below the tankless heater. This was the second tank we installed on the system, the first all copper tank had a crack flaw in the side an had to be discarded.(it broke my heart)

No need for a check valve in a normal gravity system.

Look back a few pages,
Richard was talking about a system that was in his dads house where the cold water feeding into the DHW tank would feed into a tankless coil first and then into a storage tank.So the tank was being replenished with hot water.All the gravity part of the system had to do is keep the tank hot so the gravity could be slow.Took me a while to understand how it was piped up but when I got it ,it sounded like a great system.
DON

Don
Most thermosyphon/gravity systems are just that , S I M P L E . no need to complicate what has worked well since plumbers were invented . someone once said " the simple approach is the best" I personally have come to believe this to be true.
good luck, and keep postin'

TGMC wrote:S I M P L E . no need to complicate what has worked well

Adding a check valve isn't over complicating things. As mentioned it might not be suitable for smaller coils but if you have full boiler you might want to "check" it out. The cost for us to heat hot water is nearly nothing and we for intents and purposes we have a endless supply of hot water. You'd have to be running the dishawasher, washer and take a long shower before the water starts getting colder.

...if you add an additional 100 gallon tempering tank before it enters the coil

Update: Got it finished up, and fired up last night. It didn't get as cold out as I had hoped but worked out good. Fired up at about 12:45 am checked temp this morning about 6:00 with a meat thermometer(only thing I have to check temp) and temp was about 115'. Not bad I think considering stove wasn't running flat out and probably didn't run at more than an idle for most of the time. It only had to bring the temp in the house up about 2' I added some insul. to the pipes today and will finish insul. Sat. morning. Hopefully this will help some. Also the 1st time I have run the stove using the chimney after taking off the DV. Was running about .02 on guage. Seemed to be putting out more heat. May be due to DV pumping some of the heat out of the vent. Had to run DV at full bore because the rheostat had a dead spot in it and wouldn't work except on high. Thanks to everyone for your help, it made this project much easier to complete with all of the input I have received.

Jeff

I'm glad to hear it all worked well.If in the winter you find to much hot water you can remove some of the insul on the gravity lines.

I STILL DON'T SEE ANY PICS OF YOUR SOLDER JOINTS! Jusk kiddin.

Did you use a tempering valve?
DON

Ok, now I have another question about the coil I have. It makes hot water fine and checking temp. out of tap with a meat thermometer it has been 135'-140'. This seems to be plent hot enough but I was wondering about recovery time. I know the thermosiphon method takes a while to bring it back to temp and the fact that it's not all that cold out yet so the stove isn't running full bore yet. I was wondering if having the coil bent out more ove the grate would decrease the recovery time by absorbing more heat into the coil. I will attatch a pic of current setup and see what you guys think. I know that once it gets colder out and the stove runs more it will help also. At any rate, this won't be something thats done until next summer. Thanks.

Jeff

Space out your showers and you'll be fine.

Most of the time, the coil is mounted directly over the fire, so the bottom pipe of the loop is about 6" above the grate... So yes as long as you are sure you won't damage the pipe, I'd bend it over the grate.

Greg L.

My loop is at the top of the stove. I guess the coil is about 11" from the grate.

Thanks, the coil works decent now and probably will be better the colder it gets and more the stove runs. I just wanted to ask if it would recover a little faster if it were closer to the fire. Thanks again.

Jeff

If you can bend it without stressing out the pipe I would do it but be careful. I would call the company and see if they have advice on how to bend it safely.

Here we go again, up until the other day we had only used the hot water in increments. Shower at night bath in the morning etc. I have been off this week and used more water than usual. Found out twice that the entire tank is not heating up even after approx 10hrs. Take a shower and used all the hot water in just a couple of min. Hot water is hot, and after that its just warm. Seems like the top of the tank is staying hot and lower in the tank is cooler. Do you think It's just not circulating fast enough. If so I could install a pump or any other suggestions.

Jeff

I missed this post lately.... sorry to see your back! *laughing* I'll vebture a guess that the pipe won't want to bend without heat... that is... acetylene and bring it red in two spots at once. My gut says it's thick enough that if you try to bend it cold you'll pressure the fitting and the side of the stove too hard. I'd even speak to the factory & ask. There might be some reason that it should be heated to bend it....like, if it's tempered you'll lose the temper.

As for the heating.... If you want to try a pump , try it. Is money no problem? Cheap: bronze pump, switch on wall. More: add aquastat. More: add four or five custom brazed dip tubes each a foot longer than the next and put thermometers to the bottom of each with thermal heat transfer paste. Heh heh heh....You could see the water temp at every level in the tank. *smile*. It would be interesting to know the temps at different levels in the tank. Of course if you add a pump, the temp would be even.

Even adding a pump might not give you more hot water. The tube in the stove is only going to transfer so many BTU's. Gravity tranfers them slower, but probably hotter. A pump would only mix the water. You might get some more heat, but I'll bet it wouldn't be a huge difference.