Gravity Heating at Its Finest

Alan (California Radiant) Forbes

Still working fine.

jumper

I presume tube is steel? Is water softened? Ever delimed?

Larry Weingarten

Hi, I think we’re looking at a sidearm water heater. It would have copper coils. The Bay Area has some pretty nice water.

Yours, Larry

Ironman

And still running!

retiredguy

This is what heated our stone lined hot water tank when I was growing up and by the way it had no safety control, not even a relief or safety valve on the tank. The manual gas valve was turned down to provide a very small flame to keep the water hot and if you needed more hot water you manually turned up the gas flame. ( you couldn't forget to turn the gas back down after bathing)

Around 1970 when I was working for a residential HVAC contractor in Pittsburgh, Pa. performing service calls I was sent to an apartment building that had a whole wall of these side-arm water heater coils heating individual apartments. Each heating system consisted of one of these beasts, copper finned radiation, a very small B&G pump and a T87F Honeywell thermostat. Controls such as a gas valve, thermocouple, safety pilot and a strap-on limit were added for safety. "What a sight". The owner said that he repurposed these heaters from a scrap yard for almost nothing and installed them in his building. Were they efficient, probably not, but they worked and were very cheap.

Jamie Hall

Actually, they probably weren't all that inefficient. And, being simple, they will work forever, given a minimum of TLC.

Alan (California Radiant) Forbes

Simple and elegant. 

The house was built in 1921 and this was, undoubtedly the original heat source. 

We were there to replace a thermocouple and before me, someone installed a combination gas valve. Other than that, it’s probably had very little attention. 

dopey27177

The only time I saw a set up like this was in a beauty parlor 55 years ago. At that time it was 25 years old. My service call was to replace a circ pump from the stone lined tank back to the heater.

The kiss school is the best way to go.

kiss (keep it simple stupid)

Jake

jumper

Larry Weingarten said:

Hi, I think we’re looking at a sidearm water heater. It would have copper coils. The Bay Area has some pretty nice water.

Yours, Larry

no circulator?

Jamie Hall

Didn't need it. It heated the water which rose and went into the top of the tank, in which it cooled and dropped and went back to the sidearm, where it heated and...

Larry Weingarten

Hi @jumper , Here's a photo of one that the General Society has now. No mechanical pump! Gravity works!


Yours, Larry

jumper

Larry Weingarten said:

Hi @jumper , Here's a photo of one that the General Society has now. No mechanical pump! Gravity works!
Yours, Larry

I wonder what btu of burner and surface area of coil is? If thermosyphon doesn't move water fast enough.....

Alan (California Radiant) Forbes

The boiler plate says 45,000 BTU and there's an old, Honeywell strap-on aquastat on the piping as it leaves the heater; set to 190°. If that aquastat fails in the closed position, the thermostat becomes the only safety.

I'd say the thermosiphon is tried and true after 100 years of service. It would be cool to know the actual flow rate.

Jamie Hall

Actually, as a backstop (assuming that you didn't have pressure issues...) if the water actually boiled in the coil it would condense immediately when it managed to get to the tank...

Larry Weingarten

Hi @jumper , I can answer some of the question... BTU input varied a lot, but from 15,000 to 25,000 was a pretty normal size. Coils were made in lots of sizes and went from one to three coils in a unit, so knowing the surface area would be hard without knowing the length and diameter of the coil/s.

I imagine that if the plumber installed it wrong; which would be not enough vertical height in the piping to get good flow, or if it were piped so air could block flow, the heater would likely boil and a callback would happen. There were pretty specific guidelines for a good installation... even though automatic controls and relief valves were often not part of the job.

Yours, Larry

mattmia2

Didn't the pressure relief valve not exist until the 1940's or so?

Larry Weingarten

Hi @mattmia2 , Yes it was around in various shapes long before, but didn't become code in the US on water heaters until the sixties. I think @DanHolohan has stories about the arm on early relief valves on steamboats being forced closed, so the boats could race faster. Sometimes, when the boilers blew up, it wasn't so much fun!

Yours, Larry

mattmia2

My parents' house was built in 1957 and had what i think was the original water heater in to the 80's and it had a t&p valve. It didn't have a dedicated tapping for it, it was in the outlet piping, but it had one.

Larry Weingarten

Back in the "good old days", heaters blew up almost weekly in the US. No doubt, good plumbers started adding relief valves because they didn't want to read about their clients in the newspaper. I put quite a few relief valves on old heaters that didn't have them. I'd always ask first, and nobody ever said not to do it!

Yours, Larry

retiredguy

In the early day of the water heater before the dedicated outlet was part of a tank, the installing plumber if he was safety conscious enough would add a galvanized TEE in the outlet of the tank and install a "pressure relief only" into the side outlet of the tee. When a T&P valve was added the plumber would install it into the top of the tee and the supply water was piped through the side outlet of the tee.

As I stated in an earlier post the house I grew up in had 2 of these tanks with no safeties of any kind. The gas supply to the heater coil was by a manual gas valve that was adjusted by the home owner. Many times the hot water would come out of the faucet in the bath or kitchen at or near boiling because someone turned the gas supply too high or forgot to adjust it lower after a time of high hot water usage. Those water heaters were the same as the the picture that @Larry posted except they were not painted.

Alan (California Radiant) Forbes

Correction: There is a relief valve right next to the fill valve. The owner called me after I left and said it was leaking. I told him that there was probably an expansion tank in the attic with a vent trough the roof and considering the age of the system, that vent somehow got plugged or capped.

Then I remembered him telling me about the recently done cathedral ceiling in the living room. They must have removed the expansion tank when that was done and never installed a bladder tank at the boiler.

Larry Weingarten

Hi @Alan (California Radiant) Forbes , It's good someone thought to install the pressure relief. That wouldn't necessarily have been a given with the old atmospheric vent.

Yours, Larry

jumper

Alan (California Radiant) Forbes said:

The boiler plate says 45,000 BTU and there's an old, Honeywell strap-on aquastat on the piping as it leaves the heater; set to 190°. If that aquastat fails in the closed position, the thermostat becomes the only safety.

I'd say the thermosiphon is tried and true after 100 years of service. It would be cool to know the actual flow rate.

Copper scales at 190° unless water is moving continuously. If water boils copper will burn through fast. Must have been high quality and thick soft copper in those days?

Labenaqui

Isn't Mother Nature wonderful?
We have recently patented our "Neo-Gravity Hydronic (FHW) Heating Appliance(TM)" emulating natural (gravity) convection assisted by Delta-T ECM Distribution Management.
How readily we forget natural phenomena in "modern" heating. We are typically using 8-13 Watts total distribution energy in up to 3,000 sq. ft. homes up here in "Frostbite Falls" NH, and using significantly fewer materials.
Simple, Durable, Efficient Hot Water Heating ..... Period!

retiredguy

This post is not about a "side arm bandit" as they were called in my area but as to a gravity heating system. Many years ago, when I was new to the residential heating service industry, and just out of HVAC tech school I was called to a "no heat" call in Squirrel Hill, a suburb of Pittsburgh, Pa. The house was a very large 3 story house with a gravity hot water system. I was amazed that there was no electricity going to the boiler. The only source of electrical energy used by that boiler was that produced by a Minneapolis Honeywell (as the company was called then) Pilot generator. I was amazed at the simplicity of the system, no electricity, no circulation pump, nothing. The no heat problem was a worn out limit control. Back then the contacts of the required control were gold plated to keep the resistance low since the pilot generator produced only 3/4 volts. The down fall of those systems was the high installation costs of the very large piping system and the slowness of the system to respond to ambient temperature changes

That was not my first experience with a gravity system