Are BB element supports necessary?

numberforty1

My builder put in these awful sheet metal cradles in my BBs, and I think they are the culprit of all the noise they make. They bend pretty easily though - if I just bend them all away from the element, is there any harm? The pipe element is metal, so it's not like it's going to droop or fall to the floor - is there any unseen benefit to these supports I'm not considering?

Many thanks

Big Ed_4

A pinging noise , maybe ...

PC7060

If you want to prevent noise from movement between support and the BB use ptfe sheet between the two sections. Very rugged, easily cut to size and rated at up to 500F. I’ve used the “Film with Etched Texture” version (link below) to prevent vibration noise between metal assemblies in aviation electronics, good stuff. I have a few scraps I slip under under paired feet of radiators when I’m working on them. Makes ‘em easy to move around when installing valves or lining up with unions. 

https://www.mcmaster.com/ptfe/chemical-resistant-slippery-film-made-from-teflon-ptfe/

numberforty1

@Big Ed_4 Not sure what you're saying - are the support cradles even necessary?

numberforty1

@PC7060 Thanks, I'll look into that...but really, are the support cradles even necessary?

PC7060

Well, I can’t tell from the pictures how the units are designs to be mounted but certainly something is required to secure in place. 

Is the bracket in the picture just HVAC drive cleats bent into U?

mattmia2

If the supports aren't supporting it, something is supporting it, usually the pipe where it goes through the floor or wall. It will also sag if it is more than around 8'-10' support points.

It is a bit of an art to support it to be quiet even with the right materials, you would need to have some experience to get it right the first time.

Slant Fin makes these generic suport brackets although i wouldn't use them on a section where you expect more than maybe 1/8"-1/4" of expansion at most, i don't think they can slide the way the cradles in a real cover assembly can:
https://www.supplyhouse.com/Slant-Fin-108173000-M-1-Hanger

bburd

@OP Yes, those supports are necessary. Manufacturers don’t add cost to a product without a good reason.

numberforty1

@PC7060 Yes, drive cleats What I mean is - the element is secured to pipes at both ends that go through the floor - with those pipes holding the element in place, what is the need of the drive cleat cradles? Seems to me I can just ditch them.

numberforty1

@mattmia2 Yes, the question is, can I just remove the "supports" (which are just drive cleats), since the element is held in place by riser pipes at both ends? It seems like it to me. Does it matter if it sags a little?

My thought is, to make it quiet, the best situation is not to support the element on anything unless it needs it, right?

numberforty1

bburd said:

@OP Yes, those supports are necessary. Manufacturers don’t add cost to a product without a good reason.

These were not made by a manufacturer, the builder just grabbed them because it was an easy way to make fancy wood covers. What do you think these drive cleat supports are necessary for? Thank you!

mattmia2

If there is nothing supporting it, it will twist and wedge itself in the holes where the pipes pass through the floor/walls and won't be able to move there and will lean up against the walls and bind and make noise as it sticks and releases in both those place. Even when it is supported on brackets that can move you have to make sure the pipes at the ends can move freely, both with the size of the holes they pass through and with how the fittings are arranged. 100' of copper pipe will expand about 1.5" changing temp from 60 f to 180f.

Looking at a better image of the slanfin bracket, it has a rod underneath that the piece that supports the pipe can slide on, so it should work great if you use it the right way even in a long run of pipe, disregard my comment about only 1/4" or so of movement, you just need to install it so it is centered on the rod and front to back

numberforty1

@mattmia2 thanks for your help again, I'm just not sure I follow - the element will twist?? The element is horizontal and the pipes are vertical at both ends (you can see a little in the picture), so there's no way the element could get into the holes that the pipes pass through. The supports keep the element from sagging I guess, but honestly a little sag will only bring the end pipes a little closer together, keeping them from rubbing against the holes in the floor they go into. Let me know if I'm misunderstanding this twisting you mentioned

bburd

@numberforty1 there is a limit to how much sagging the pipe those fins are mounted on will tolerate. All structural materials deflect over time; and deflection in a beam, which the pipe represents, is proportional to the FOURTH power of its length. Do the math and you will see why those supports are there. Water is heavy. Copper is soft; it bends easily.

The builder was probably well aware that baseboards need support along their length, because he has previously installed the factory made product. His solution just wasn’t as well designed as the manufactured ones.

numberforty1

@bburd @mattmia2 Yes it makes sense the element can't run for miles without any support, my thought is to bend these sheet metal cleats down away from the element, then stuff a high density foam and milk jug plastic strips between the cleat and element, so it is still supported, but the cleat cannot touch it or heat up from it. A home made solution at best, but one that seems viable based on everyone's comments. Appreciate your expertise, let me know if you have any other suggestions, happy to hear them. Thanks again

mattmia2

If the only thing supporting it is the pipes it is going to cock one way or the other until it wedges in to something that will support it, weather that is up against the wall or the enclosure or up against the holes the pipes come through or something around the pipes below it. It will stick at whatever that point is until the expansion produces enough force for it to move then it will suddenly move with a pop or ping or squeak.

pecmsg

3/4" copper pipe should be supported every 5'

mattmia2

If you try to make something homemade, you will need 2 smooth surfaces, one that rests on the bracket and one that rests on the fins and makes them in to a smooth surface so they can slide against each other. Without something bridging the fins they will plant themselves pretty firmly on whatever is nearby.

PC7060

Oh my goodness @numberforty1! Rather than use a milk jug, spend the 20 bucks get the Teflon sheet I recommended. Guarantee the copper vent will not gain purchase or wear on the smooth side. Cut it to size, slip it in there and forget about it.

One 12” square will make enough for 24 brackets at 1”x6” 

numberforty1

Thanks @PC7060, I am looking at them, haven't used it before. How thick a sheet do you think you can cut with a basic razor or scissors? I'd want something thick enough to retain its shape.

PC7060

Material I mentioned is easily cut with scissors. I included a screenshot of the MMC catalog below of the type.  

Here is a picture of it under the feet of a radiator during install. The slippery side is down. For your purpose I would put the slippery side up against the copper baseboard element. The brown coated side would be down against the metal brackets

numberforty1

@PC7060 Thanks again, I'm going with the PTFE sheets at 1/32" to insulate the brackets from the heat, but it looks promising. They said both sides are pretty slippery, even though one side is etched, is that true from what you see? I'd never used McMaster-Carr, they actually mailed me the stuff before I even entered payment info - I've never seen that in my life. They were helpful on the phone though, seems like a good company.

PC7060

Etched side is similar to smooth cardboard in friction and can be taped or glued.   Slick side is slippery as, well, Teflon!

yes, MMC ships quickly although they make us pay first!! Good company!