Gravity Hot Water Heating Q&A

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Gravity Hot Water Heating Q&A

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Daugherty

Great article. How do I find a contractor to perform a conversion from a gravity feed system that supplies two floors with four radiators on each floor. A couple of options... 1) I would hire someone who truly understands what they are doing to do the job. 2) I would provide any information to someone remotely to have the system designed and then hire someone else to install the new circulated system. 3) I would provide any information to someone remotely to have the system designed and then I can install the new circulated system myself. Thank you, Carlton Daugherty

Jamie Hall

@Daugherty -- your best bet, by far, is 1 -- if you can find someone. Reason being that there are always unexpected items which come up while the job is in progress.

newagedawn

where are you located?

Daugherty

Yes. I would rather go with option 1.
However, I bought the home two years ago as a foreclosure in January outside of Iowa City, Iowa. We had to replace freeze busted boiler, hot water heater, and six cast iron radiators on a rushed schedule. Received three quotes for the new system and went with one of the two higher bids from a highly rated shop. None of the three shops ever performed or offered to perform a heat load/manual j calculation on the house. Selected a Weil-McLain high efficiency boiler with one of their indirect fired hot water heaters. Replaced radiators in first floor and second floor radiators with matching ones out of Chicago. Two radiators in basement were replaced with fin and tube heat exchangers. (I have since learned enough to know that this was not a good choice.) I have been looking at a new A/C for the house and every company that comes through has a different comment about the boiler system (this should be done different, that should be plumbed this way, it requires yearly maintenance to not become an expensive paperweight [I am still waiting for a quote from the installation company for said maintenance work]). Still have not had any AC contractor believe that a Manual J calculation is necessary. It all leads me to be very wary of turning someone loose on my radiators' plumbing.
My reason for wanting to convert from an gravity up-feed system to a circulated system is because I am tired of ducking under the large pipes in the basement. I also wonder if I could install thermostatic radiator valves on the radiators and end up with zoned system that provides more appropriate heating. Potential heating cost savings would also be a bonus that my wife would appreciate.
How does a person go about finding someone competent to evaluate, design, and modify the system?
That is why I am considering working with someone long distance to design and spec out the system, and then I would feel confident hiring the local heating company to follow the established plans.
Thanks,
Carl

Harvey Ramer

I just did a house not to long ago, that is very similar to what you describe.
On that job we removed all the old piping and plumbed the radiators with PAP tubing that was fed off of a manifold. Each radiator has been fitted with a TRV and the system runs on continuous circulation, which automatically shuts down when it gets warm outside. The boiler is utilizing an aggressive ODR curve, which greatly enhances the systems efficiency. There is no thermostat in the house and every room is exactly the right temperature.

A setup like this requires considerable design work and planning. It is worth it though. At the end of the day, this guy had the lowest gas bill ( per sf ratio ) on the block.

Daugherty

Mr. Ramer,
Thanks for the response. You present some new terms for me to research (continuous circulation and aggressive ODR curve). It sounds like exactly what I would like to accomplish. Each radiator has its own pair of pipes dropping all the way down into the basement and I was imagining replacing iron pipe with 'plastic' tubing only in the basement sections. But your post makes me think that maybe running the PAP tubing up the walls might not be such a difficult project.
Might you have any pictures from this project?
It would be fascinating to see the transformation.
Thanks for the suggestions.
Carl

Henry

This was the Northern Electric building. It is a single pipe gravity hot water system usin O-S fittings. There was sufficient distance between the T O-S and the radiator to be able install a TRV.

JUGHNE

Carl if your second floor pipes are separated in the basement and already hidden in the walls maybe consider just reusing them.
Most dedicated 2nd floor risers are 3/4-1" pipe from the few gravity systems I have seen.

The_Ghost_13

All of this is very intriguing to me as I watch a number of the shows on TV that involve the off grid lifestyle. Although that is not for me, I am wondering if this idea could be combined with in-floor radiant heat and either a masonry heater or wood stove? My wife and I are planning a barn conversion to home and I believe that if this were possible it would be ideal. Please let me know of any and all thoughts.

jonfs

Wow! What an amazing article.
I'm just finishing an install of a second wood boiler stove system here in South East France. The primary heat sink radiator is getting hot at the top, but not at the bottom... I'm hoping this old rad is gunked up, or maybe I need to replace the taps with straight-through pipes - and the problem isn't that it's only a metre above the top of the boiler stove... "0) comments welcome!!

boiler1927

Great Article !!!! and I'm hoping someone can help me out I have a 1927 International Economy Boiler and I'm looking for the Flame Diverter !!!! no one knows anything about it THX

Erin Holohan Haskell

@boiler1927, I recommend you start a new discussion about that. Thanks!

pieIX

Hello,

In the answer of the “Q: Is that a bad thing?”, you say that the boiler design at 150F @ outdoor design of 0 is good. I assume this temperature is in the primary loop.

If I use this formula to determine the heating curve :

Heating curve = designe supply temp - room temperature
room temp - designe outdoor temperature

1.14 = (150F – 70F) / (70F – 0F)

You have a heating curve of 1.14. The outdoor design where I live is –9F. So if is use the same heating curve with –9F outdoor design I have 160F in the primary loop. On my system, the difference between primary/secondary is 25F. So the boiler will run at 185F.

Where do you put the pressure when you start the system at 18psi an you have 13.2 gallons in your expansion tank and the safety valves is at 30psi?

My system boiler design for now is at 138F (0.80 heating curve) and I can’t go higher then 132F (on the boiler 29-30psi on other gauge glass 26psi) if I do not want to bust the safety valves at 30psi.

Also, can you balance this radiator with the valve on the radiator?

Thanks

jumper

Henry's post is interesting. Eight floors with gravity? And one pipe? Was it overhead distribution?
Love to be fly on the wall hearing why original designers decided that way.