1908 Victorian baseboard to cast iron rad conversion project

MarkZeh

Hello Wall folks, as title says it starting to convert the ugly baseboard rads (BBRs) in the house back to original CI rads. Appreciate all thoughts and advice. First conversion is Zone 3 for the back great room extension. Piping was simple, supply line leaves Pearless HW boiler, enters into first 17.5' section of BBR, then crosses room (sq room ~18.5' x 20'), via flex tube, where it then passes through another BBR of 15' before returning back to boiler. BBR is standard 2.5" by 2.5" not sure of manf, maybe slantfin. Based on room window layout planning on installing 2 - 20 sec (4" wide) CI rads on west side with east side receiving a single 34 sec (4" wide) CI rad. Previous and proposed layouts look good from a Btu stand point. Question for me comes down to the hydronics, supply and return diameter piping as well as Y-splits and zone valves. Kindly see attached original layout and the new proposed one.

Facts: all current piping is 3/4" copper. Ball valves to control supply and return with a single gate valve for zone drainage.

Understand that the 2 CI rads on the west side cannot be connected in series due to 'run-through'. With that said my plan is run separate supply lines to those rads from 2 supply Y-splits. First Y-split, divides the supply between east and west, 34 sec vs 40 sec, close enough, I think, for 50/50. With a second Y-split dividing the west side supply line between the 2 - 20 sec CI rads. From here both east and west side will rejoin as a return to boiler. From a zone-valve control standpoint, should I have 3 separate return shut off ball valves installed to be able to isolate (drain) each of the 3 CI rads separately? make sense, or 2 valve for east/west side radiator separation. Kinda like the 3 return shut off valves myself.

Next: prior to primary Y-split, should piping be upgraded from 3/4" to 1" and leave balance as 3/4" or is 3/4" across the entire zone sufficient.

Lastly: planning on leaving supply and return lines closest to boiler in copper as they presently are with balance piped in hydronic pex for cost and ease of install.

Any comments/questions/thoughts/considerations/ or possible psychiatric recommendations welcome. Trying to restore her to her original beauty. Zones 1 and 2 to follow.


Thanks to all in advance.

mattmia2

If you attached something, it didn't show up.

You should do a heat loss so you know what output you are trying to get from the new emitters. That being said, if you are running the same water temp and the baseboard heated the room, you will be transferring enough heat with the same size piping, the question is more about if the radiators can emit that much heat or if it is way too much.

Is this truly a separate zone with a separate thermostat and zone valve or circulator? It will heat very differently than the fin tube baseboard if that is what is in the rest of the house.

MarkZeh

Mattmia2, many thanks. Performed a heat equivalency analysis between the BBRs and the CIs. BBRs: ~32.5' total length @ 600 Btu/ft (2.5" x 2.5" slantfin), totaling 19,500 Btus original BBR heat output. replacement CI Rads at the 20/20/34 section, same water temp, total 24,752 Btus. Higher Btu than previous but thought was that I could always 'tool down' the flow to 34 sec CI Rad if room gets too hot. Will try to upload layouts again.
Thanks Matt

EBEBRATT-Ed

You need the btu output of the radiators you are using at the water temp your running. and you need to know that the radiation will heat the space.

Only then can you size the pipe

MarkZeh

Mattmia2, Hi, apologies, missed your other question, separate thermostat, separate zone valve/circulator pump. All 3 functioning zones in the house operate off of separate thermostats and separate zones/circulator pumps.
thanks again

MarkZeh

Ed, thanks for you insight. Btu output for the CI rads is based on the rad dimensions (LWH) and # sections, coupled with the rads square EDR as tabulated by the rad's manufacturer. That EDR value vs the water Btu output @ boiler water temp of 180 deg was used to determine the Btu output for each CI rad. Anything else I should take into account?
thanks

mattmia2

You should really do a heat loss. You don't know if they sized the fin tube to the load or if they just put it wherever they could fit it. That will give you more insight in to how much flow/what supply water temp you need. If they are very over sized you could have issues with overshoot. The anticipator in the thermostat can help with that but it is better if it doesn't have to try to end the call before the radiator is full of 180 degree water that is going to overheat the room over the next 45 minutes.

EBEBRATT-Ed

@MarkZeh I agree with @mattmia2

A heat loss would be good. You could calculate your supply water temp. The lower the water temp you run at the more $$$ you save but with a CI boiler it has to be piped right for this to work

MarkZeh

Mattmia, clear, will perform a heat loss study on room and see what the requirements are. From what I have see thus far of the house (just purchased it in late Oct) the plumbing appears to be spot on and professionally done. Never know thou. Let's see what the heat calculator comes up with and we'll chat more.
thanks

MarkZeh

Mattmia2, OK, ran an on-line heat loss calculator that took into account room dimensions, windows, doors, insulation levels etc. Results:
Total Heat Loss for 60o F Temp. Diff. = 14,009.00
Total Heat Loss for 70o F Temp. Diff. = 16,530.62
Northeast sees some cold nights, last few years maybe Teens at night, keeping room at 68 F would be 60 deg diff at best. Appears that the 32.5' of fin tube was oversized for the room. That amount of BBR would put out ~19k Btu. Perhaps the the thermostat in the room itself was purposely installed there to mitigate that BBR heat output by zone control. So looks like the Btus from the proposed CI rads are way oversized.
Next steps?? Thoughts

EBEBRATT-Ed

You can use the CI rads just use a lower water temp. But your return water must stay above 130 degrees. Running a lower water temp will save on fuel.

There are charts that show the output of the CI rads at lower temperature.

Maybe someone can post one. If I find my copy I will do that

MarkZeh

Ed, thanks, appreciate all data sent. Only issue I will have for now is that there are 2 other zones on BBRs. Zone 1 (1st floor) will be changed from BBRs to CIs this summer when I shut down system for the season. If all goes well, Zone 2 (2nd floor) will be changed as well. A little more work thou. Meanwhile, outside of some extra $$ blown on fuel, any issues running the CIs at a higher temp? positive thou that the return temp will be higher than 130. Meanwhile, I need to review which CI rads I'm going to use in that big room. No need to over size the heat output.
thanks

Ironman

EDR tables:

You should use the AVERAGE water temp, not the SUPPLY water temp to calculate the output of the rads. Usually, that’s 170*.

MarkZeh

Ironman, huge thanks for the info. Have EDR values from the rad manf, some of which I downloaded from this web site. Rad Btu output came down once I used 150 instead of 170 as a BTU/SqEDR value. Although is appeared that the BBRs used in the great room were over sized, 32.5' @ 600 Btu/ft: 19,500 Btu for a room with a 16000 Btu requirement. Not the end of the world if the BBR is a little oversized, just a waste of $$. The room thermostat controls the temp anyway. Meanwhile, the CI rads I'm considering to replace the BBR now totals 21,800 Btu (based on the 150), a lot closer to the original 19k. Looking good. Have a simple plumbing question for the supply line. As I am avoiding 'run-through' by piping a separate supply line to each of the 3 CI rads, I will need to first split the supply line to the 1 CI rad on the east side from the supply to the 2 CI rads on the west side. Thereafter I will need to split the supply line going to the 2 CI rads on that west side wall. Question: what type of Y split should I use?? I see true-wyes and the other type. Does it matter. I'm maintaining the same line diameter throughout, 3/4"
thanks

mattmia2

Just use a tee to branch off. Half inch is sufficient for the parallel branches to the radiators. You will want some sort of balancing valve on each radiator. If you install them with radiator valves those can be used for balancing.

MarkZeh

Mattmia2, awesome that was the plan, valves on all three CI Rads. Also going to install 3 shut off valves on the return lines, at the boiler, if some reason I need to remove a single rad, just have to drain down that line and not the entire zone. Any issues if all supply and return lines are left at 3/4"? Can do 1/2" np.

The Btu outputs for the 3 CI Rads are:

Great Room: Sections Btu output
2-1/2" x 2-1/2" slant fin style 34 12240 CI Rads
210 ", 180" total: 390" (32.5') @ 600 Btuh/ft: 19,500 Btu 16 4800
16 4800
21840 Total Btu

MarkZeh

Mattmia2, hello, sincere apologies for the radio silence regarding this part of the project/renovation. The CI Rads are not restored, installed and piped. Wow do these bad boys put out heat. May need to tool them down in time but with winter being here and the wood floor sits on top of a concrete slab, the extra Btus are more than welcomed. Thanks for all your advice. Next project is the CI Rad install for front foyer, LR and DR. Keep you posted.
thanks!

Mad Dog_2

Nothing like freshly-coated wood floors. Looks good. Mad Dog

MarkZeh

Anyone: looking for an EDR value for a CI Rad that I need to install in the house foyer. She's a Weil Mclain, thin tubed old steam Rad obtained from a renovated Brooklyn brownstone. Stats: 6 Tubes, 25" high, 7 1/8" wide, 28.75" long with 16 sections. Cross chart referencing between Burnham, Capitol, Aero etc is ranging from 48 to 60 EDR Ugghhh. Anyone have a documented specific value from WM? Appreciate all/any help. Thanks
mark