I have a 1500 sq ft house that is currently heated with large CI radiators, and appears to have been converted from a coal fired gravity system to a gas fired circulated system. I recently gutted a partially finished basesment, shored up and sealed the foundation, added a sump system, in preparation to refinish the basement into more useable space. In doing this I am adding a subfloor which now makes the old gravity feed lines a forehead busting hazard. So I began investigating moving the pipes into the joists. I had several plumbers come out and give their opinions about how it should be done, and I also have done quite a bit of research on line and in forums like this trying to determine the best way to get this done. Much of what the plumbers suggest seems to contrast the info I've read here, but after some prodding, most of them don't have much experience with this type of project. Based on this I think I have made the decision to take on this project myself, with the knowledge I've gained from research, hopefully along with some help from the experts here.
Here are some of the details to start with: My Boiler is a Weil-McLain CGr4-SPUN with 88,000 BTU Output Heating Capacity. My circulation pump is on the return side, and it is a Taco 007-BF4-JW. I also have a large galvanized expansion tank. There two a large (3”) CI supply and return lines feeding the system, and all of the radiators tee off of these lines (one to supply and one to return). There are 7 radiator runs out of the basement, 3 of these go to the 2nd story bedrooms (one of which tees off in the floor somewhere to split between one of the bedrooms and the bathroom), then there are 3 radiators in the dining/living area, and one in the cabinet under the kitchen sink. I estimated the EDR and Heating capacity for each radiator (using the method described here: http://www.columbiaheatingsupply.com/page_images/Sizing Cast Iron Radiator Heating Capacity Guide.pdf
) and the capacities are as follows:
7650 BTU/Hr & 5950 BTU/Hr (13600 together - these are the two that share a feed from the basement)
7140 BTU/Hr (This is the one under the sink).
Totaling 72,250 BTU/Hr for the entire system.
I’m planning to eliminate the radiator in the kitchen as it is only effectively heating the undersink cabinet while the rest of the kitchen remains pretty chilly. I’m exploring other heating sources for the kitchen, but that’s a topic for another day.
Some preliminary plans for this system. Demo all of the cast iron piping in the basement, and change to Pex-Al-Pex (probably the FostaPEX by Viega). Rather than run shared supply/return lines with a lot of tees, I plan to run individual supply and returns to each CI radiator from manifold at the boiler. This idea really appeals to me because it will allow me to balance the system from one location. Here is the manifold I was thinking of using https://www.supplyhouse.com/Viega-15906-8-Loop-ProRadiant-Stainless-Steel-Manifold-Shut-Off-Balancing-Flow-Meters
. I plan to purchase an 8 loop manifold and only use 6 runs in case I decide at some point to add a run for a basement bedroom radiator or possibly somewhere else. I’d just cap the two unused runs at this point.
I also plan to replace my galvanized expansion tank with a newer bladder unit, but I’m not sure how to go about sizing that. I have also considered changing the circulation pump to and ECM pump, but I don’t know much about them. Taco makes a variable speed ECM pump that has a delta T sensing function that sound good in theory, but has some mixed reviews. See http://www.tacocomfort.com/products/variable_speed_products/vt2218/index.html
. Several people have also suggested that I add a Spirovent air separator also, sounds like a good idea to me.
I am definitely not a pro when it comes to plumbing, but I’ve done a little here and there, and I’m a fast learner. I feel like I have a pretty good grasp of the situation, but perhaps I am overconfident….. I’m really looking for pointers or advice on any aspect that I may have overlooked in the process or anything in the above that looks suspect. As well as opinions and input on the FostaPEX, Manifold, ECM Pump, Expansion Tank and Spirovent. I have some specific questions too, but this is already turning into a novel so I will stop here for now and ask some questions as the discussion thread starts.