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OT: question for HVAC folks who know hot water heat systems

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  • #16
    Originally posted by Sparky_NY View Post

    Jerry did say it had the old cast iron radiators so its a pretty old system. Many of those old systems did not even have a circulator pump, they were gravity flow systems. If there is no pump, all that is needed to keep the heat on is a tiny ac source just to operate the thermostat / gas valve, a amp or two. If there is a circulator pump and its the new minature type they are pretty low power and wouldn't take much to provide backup power for.
    He said hot water, which requires a circulator, as opposed to steam, which does not. I do not see where he said cast iron, but there are many 1 pipe cast iron steam rads that were converted to 2 pipe hydronic, in addition to cast iron baseboard rads. My steam system in another house has a blower powered burner rather than a passive airflow burner like many, but not all hydronic boilers. One of my hydronics is a 'hi efficiency' that has a blower on the vent.
    Location: Jersey City NJ USA

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    • #17
      I had a "Gravity" Hot Water system and it did not need a pump, so they do exist. I converted over to cast iron baseboard i.e. Hydronic Radiators and a pump to improve the system.
      As Sarky said. the new pumps are very efficient and a simple power supply could assure continued operation.
      You might even consider a solar panel and a inverter as a backup
      Rich
      Green Bay, WI

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      • #18
        Originally posted by gellfex View Post

        He said hot water, which requires a circulator, as opposed to steam, which does not. I do not see where he said cast iron, but there are many 1 pipe cast iron steam rads that were converted to 2 pipe hydronic, in addition to cast iron baseboard rads. My steam system in another house has a blower powered burner rather than a passive airflow burner like many, but not all hydronic boilers. One of my hydronics is a 'hi efficiency' that has a blower on the vent.
        Gravity flow hot water systems did indeed exist and were reasonably popular many years ago.

        Here you go, read about them https://duckduckgo.com/?t=lm&q=hydro...=v280-1&ia=web

        Last edited by Sparky_NY; 09-04-2021, 05:11 PM.

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        • #19
          Originally posted by Rich Carlstedt View Post
          I had a "Gravity" Hot Water system and it did not need a pump, so they do exist. I converted over to cast iron baseboard i.e. Hydronic Radiators and a pump to improve the system.
          As Sarky said. the new pumps are very efficient and a simple power supply could assure continued operation.
          You might even consider a solar panel and a inverter as a backup
          Rich
          One of those old gravity flow systems if it had the old thermopile type gas valve would operate with no external electricity needed.

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          • #20
            Originally posted by Sparky_NY View Post

            Gravity flow hot water systems did indeed exist and were reasonably popular many years ago.

            Here you go, read about them https://duckduckgo.com/?t=lm&q=hydro...=v280-1&ia=web
            Fascinating. And even more of a horrorshow to balance and troubleshoot than steam! My area was built up with coal heat in the mid 19th century, all heating systems in the brownstone/tenement neighborhoods are retrofits, and yet I've never seen one of these. They must have been the 1st to be retired in favor of other systems.
            Location: Jersey City NJ USA

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            • #21
              Sparky is correct. In fact, the target system was built in 1914 as a gravity flow system. Big 4" or 5" pipes out of the boiler, which was coal fired back then.

              System balance? Naw.... just the old "valves" that basically only ever "discouraged" flow, they never quite shut it off. Worked OK, but my bedroom was at the end of the system, and had 7 windows. Good thing the radiator was a long low type right up the side of the bed.

              That old asbestos covered boiler cracked decades ago and was replaced with a small gas boiler. The old one had been converted to oil, then a different oil burner, then gas, and was gas when it cracked. The only asbestos in the system was on the boiler though.

              Around here, many houses still have asbestos insulation that looks just like one-sided corrugated cardboard rolled up around the pipe. Great for freaking out the worry-warts when they look at houses. (ours has none)
              Last edited by J Tiers; 09-04-2021, 06:05 PM.
              2730

              Keep eye on ball.
              Hashim Khan

              Everything not impossible is compulsory

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              • #22
                Originally posted by J Tiers View Post
                Sparky is correct. In fact, the target system was built in 1914 as a gravity flow system. Big 4" or 5" pipes out of the boiler, which was coal fired back then.

                System balance? Naw.... just the old "valves" that basically only ever "discouraged" flow, they never quite shut it off. Worked OK, but my bedroom was at the end of the system, and had 7 windows. Good thing the radiator was a long low type right up the side of the bed.

                That old asbestos covered boiler cracked decades ago and was replaced with a small gas boiler. The old one had been converted to oil, then a different oil burner, then gas, and was gas when it cracked. The only asbestos in the system was on the boiler though.

                Around here, many houses still have asbestos insulation that looks just like one-sided corrugated cardboard rolled up around the pipe. Great for freaking out the worry-warts when they look at houses. (ours has none)
                Boy, that description brings back memories, bad memories.... I worked on a few of those old systems years ago and replaced some of those boilers. Getting that old pipe apart to adapt to copper for the new boiler was not fun, neither was breaking up the old boiler with a sledge hammer to get it out of the basement. Then there was the black slime that was supposed to be water.

                Probably have nightmares tonight now thanks to you !

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                • #23
                  Just be aware that antifreeze will reduce the amount of heat that can be transferred. Probably not a problem, unless your system is already marginal.

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                  • #24
                    Originally posted by J Tiers View Post
                    Sparky is correct. In fact, the target system was built in 1914 as a gravity flow system. Big 4" or 5" pipes out of the boiler, which was coal fired back then.

                    System balance? Naw.... just the old "valves" that basically only ever "discouraged" flow, they never quite shut it off. Worked OK, but my bedroom was at the end of the system, and had 7 windows. Good thing the radiator was a long low type right up the side of the bed.
                    Curious, how big is the pipe at that 'end of the line' rad? I just can't believe enough BTUs transfer using only convection!
                    Location: Jersey City NJ USA

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                    • #25
                      Originally posted by gellfex View Post
                      Curious, how big is the pipe at that 'end of the line' rad? I just can't believe enough BTUs transfer using only convection!
                      A lot has to do with the pitch of the pipes, hot water rising and cooler water settling lower. The big main lines are to minimize any flow restriction being only gravity/convection. They did work well though. Those were the days of pipe fitters, few can do that sort of piping these days.

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                      • #26
                        A glycol mixture is used in every commercial building I have worked on in the last 20+ years for both heating and cooling systems. Some systems use the same piping for both.

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                        • #27
                          Originally posted by gellfex View Post
                          Curious, how big is the pipe at that 'end of the line' rad? I just can't believe enough BTUs transfer using only convection!
                          About 2".

                          The radiator got plenty hot, it just took longer for it to do so than any other radiator in the place. It was really the 7 windows that caused the problem, two walls of the room were essentially all windows except for a bit at the corner where they joined. Could get a bit chilly at -29F.
                          2730

                          Keep eye on ball.
                          Hashim Khan

                          Everything not impossible is compulsory

                          Comment


                          • #28
                            Originally posted by gellfex View Post
                            Curious, how big is the pipe at that 'end of the line' rad? I just can't believe enough BTUs transfer using only convection!
                            You mean the flow pipe ? 3 " of 4" or 2 " . Depends on the length of the run and the location of the boiler

                            BTU was controlled by the number of sections you made the radiator.. thats right, you could add or subtract sections . They were assembled with double taper nipples
                            and we put them together with white lead and big clamps . There was threaded rod for holding the assembly together , but didn't trust that. .
                            You could see when the radiator had added sections as the return pipe was folded under at one end under the radiator so the floor didn't have to be torn up

                            Rich

                            Green Bay, WI

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                            • #29
                              These radiators, and, I believe, all radiators made for thermo-syphon (spelling intentional) operation, had both pipes at one end. The hot pipe came to the top, and the cold return came from the bottom. That would be correct for the flow.

                              You could add or subtract with no concern for anything but the threaded clamp rod lengths. And, of course, anything solid in the house that might block it, such as a wall, etc.

                              The largest pipes are in the basement. Then the pipes up in the walls and across in the floors were all the 2" size or so.
                              2730

                              Keep eye on ball.
                              Hashim Khan

                              Everything not impossible is compulsory

                              Comment


                              • #30
                                Originally posted by Sparky_NY View Post

                                Gravity flow hot water systems did indeed exist and were reasonably popular many years ago.

                                Here you go, read about them https://duckduckgo.com/?t=lm&q=hydro...=v280-1&ia=web
                                I love this thread, My Cusin, JJ.

                                Boiler stuff? He learned in NY, for years.

                                Came to the west coast and had to make a large body of water warm enough so the actors could act.

                                JJ heated a lake.. My

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