Stacked Cast Iron Baseboard

maine_way

Hello All,

I am retrofitting an 1890 victorian with cast iron baseboard. I have acquired the baseboard used. I will install a NG condensing boiler, so I am looking to maximize radiation in each zone to minimize water temperature. Every room will be its own zone.

I plan to stack the cast iron baseboard along exterior walls. I am thinking to pipe them as a loop run along the wall, supplying to the bottom unit and returning through the top unit. I am not sure if this affects the connected top piping (to bleed the system), especially for the for the bottom unit, or if it matters, since it can be bled from the top baseboard unit. Refer to diagram.

I also wonder if the top pipe of the bottom baseboard is not required for air at this point, since it's not the high point in the system, and could be used as another run for the boiler water, so the loop could make three passes and the pipe would return on the opposite side?

hot_rod

Do you need to supply and return on the same end?
Piping them parallel would be the highest average temperature across the board, highest output

Ironman

You should have new push nipples and the draw tool before installing them. Put the coin vent at the highest unused tap.

As hot-rod said, parallel piping is better than series.

I wouldn’t make small zones with a mod/con boiler unless you also install a buffer tank to prevent short cycling.

Ironman

If you Google “BaseRay installation”, you should be able to find Burnham’s manual that will give you all the details.

maine_way

Thanks for all the help here. I am new to the forum and really impressed by this resource!

hot_rod

For downstairs applications I have the option of supply and return from opposite sides, since I have an open basement. So that's easy.

For upstairs, I will supply and return from the same wall. I have Interior walls that are balloon framed, so I can do all vertical runs in a single cavity, and access two bedrooms from each vertical chase.

In order to run them parallel upstairs upstairs I would need to add a return pipe along the wall, or I could use the top of the lower unit to return the water, since it is not required for venting? This would restrict the flow some, since two pipes dump into one.

I was concerned about short cycling. The usage for the house is that some rooms may be seldom used. So, if I do many small zones I should have a buffering tank. Is it also possible to combine zones (i.e bedrooms zones) and add a thermostatic valve to each room? Will that be effective? Is it better or worse than buffering tank?

Ironman

This is good advice on the new nipples and draw tool. Many of the sections are still assembled. Should I undo the bolts and pull them apart and scrap the nipples and start from scratch?

Burnham’s manual has a lot of good information. Thanks for that resource!

Ironman

If they're already together, then I'd pressure test them before installing and make any necessary repairs. If nipples need to be replaced, clean the socket thoroughly and apply RTV right before assembly.

Combining zones is a good idea to help reduce short cycling, but TRVs may actually increase it somewhat. Remember, a TRV cannot initiate a call for heat, it can only limit it. The exception being if you put TRVs and all the rad's and placed the system on constant circulation with a delta P circulator like a Grundfos Alpha. That would be a Cadilac system.

A word of caution about keep some rooms set back: the pipes feeding the rad's in those rooms may freeze if they're run through unconditioned spaces like outside walls.

maine_way

Hello Bob,

That makes sense with the pressure test, especially since it's used, has been handled, and took some abuse in the demolition. Most sections look fine on initial inspection. The biggest issue I can see is that 2 sections broke apart, so the flange to take the tie bolt is broken off. I was considering a more robust system to secure it agains the wall at the seam to keep the pieces mechanically fastened.

I really love your idea of a constant circulation with TVR's. Perhaps divided in two zones, one up and one down. This would require an unbroken loop of pipe that would feed each radiator if the valve opened to allow flow? Does that mean the circulator never turns off? Or the circulator can see when there is no TVR open, and that will cancel call for heat from the boiler and shut the pump? So, there is no thermostat, only adjustment at each radiator?

This is an excellent point about rooms not in use. I typically heat them to 55 to be sure it still calls on very cold days. I've had that problem before, but fortunately it was in a pex line and there was no rupture.

Shawn

hot_rod

Correct you are that a system with a boiler that is a fixed output, most cast boilers are, can suffer short cycling with small micro-loads. It may be tough to "control" that away, sometimes a buffer tank is the best 100% fix.

With some site data and a bit of number crunching you can play around with buffer sizing and options. Formula on page 28, but read the entire journal.

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf

Ironman

IDK if you'll be able to use the sections where the flange is broken without actually seeing them. The draw tool uses that area to pull the sections together, so if it can't attach, they may not be useable.

We've found that in addition to the tool it helps to place the end of one section against a wall and gently tap the end of the opposite section with a board and a mallet while pulling with the tool.

Ironman

A delta P Circ senses when a valve opens from pressure differential and adjust its speed to match. When nothing is open, it doesn't run (essentially).

MikeL_2

As mentioned, pressure testing is a good idea. Be careful when moving the baseboard through finished areas of your home; they can drool dark black fluid. We prefer to carry the assembled sections upright - less chance of flexing the joints.

maine_way

These are all very helpful suggestions. I've never worked with this product before.

Ironman: the manual was an excellent source and took me back to my original question. Of course it's been done and is a topic covered by the manufacturer!

If I supply and return from same end, piped as shown in the included (manufacturer ) image, does this function somewhat as a parallel installation because the water would supply from the top of bottom unit and supply from bottom of top unit, and return from the top of top unit and bottom of the bottom unit?

Ironman

There would be a somewhat reduced output because the rads are in series, not parallel, if you do it like that. I think the manual shows the different output rates for each piping arrangement. That's going from memory, so I may be wrong on that.

LuckyDev

Hi there, I've been doing the same thing using cast iron baseboard in an old house. One thing to think about when installing previously used cast iron BB is that for me, just about every piece I've acquired tested positive for lead paint. It's not a deal breaker necesessarily, but if you know there is lead on them and don't strip or encapsulate it, you'll have to disclose it if you decide to sell the house. It might save you a headache down the road. My $.02 anyway. Good luck with it, it's heavy work for sure.