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fred54 10-12-2011 06:57 AM

hot water baseboard flow question (long)
Just bought an old house and am learning the ropes on baseboard. I am lucky to have cast iron baseboard but I am curious about a couple of things. I assumed wrongly that it would be piped in series, through one radiator then another but my small system (1300 sf house, 2 zone) is fed with a 3/4" copper main that has 1/2" copper tees that split off to the baseboard and then back so they run in parallel at that point. Since it is 50 years old and works fine, I'm assuming that heat always flows to cold so the system heats evenly even though my naive assumption would be that the water takes the path of least resistance and would just flow through the 3/4" pipe.

Anyway, the question. The system is drained as I am removing and rearranging a baseboard or two. While it is drained, I want to prepare for the future bathroom renovation and install a ball valve in the basement on both ends of the piping for the baseboard in a bathroom I plan on renovating over the winter. This way I can remove that baseboard and not drain the system so I will still have heat. As I said, it is fed by 1/2" copper and I am concerned that if I use a 1/2" ball valve it will restrict the flow so my plan is to sweat 3/4" adapters and 3/4" ball valves to allow more water to flow. Waste of time?

(When I drained the system, I had to fill 5 gallon pails and lug the water up out of the basement-no sump pump. Not a big deal I could use the exercise but after dumping 35 gallons of water and still having a lot of flow I luckily heard my well pump kick on it was then that I realized I had an auto-fill feature. I may have still been lugging water if I hadn't heard that. Live and learn!)

Thanks in advance for your advice.

REP 10-12-2011 05:21 PM

I think you may want to look up "monoflo tee".See some piping diagrams using those.

fred54 10-13-2011 01:57 PM

Fantastic. Now it makes perfect sense and upon closer inspection I have a monoflo system. You have helped me immensely as there is one short section of radiator which I removed completely and will not reinstall but now I know that I need to install a bypass or remove the monoflo completely to ensure my system will still function properly.

Still think I'm going to install the 3/4" valves though, it would appear to make sense.

Thanks again.

biggles 10-13-2011 04:59 PM

next time you have the system drained just below the basement ceiling...add a tee with a threaded female on the bull and slam a 3/4 petcock valve in there then in future work just shut the boiler feed and open the new petcock and drain right out the basement window if none put a pipe thru the foundation the risers and upper floors

beenthere 10-14-2011 03:39 AM

If you use full port ball valves, then there is no need to use 3/4" ball valves. 1/2" full port will not restrict flow.

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