Replacing 1/2 iron with 1/2 copper good idea?

sixplex

So this rad isn't heating too well.

Up top is 1/2 iron is connected to 1/2 copper below
Copper is about 15% smaller on the inside.


Will replacing 1/2 copper with 3/4 copper give more btua to the rad?

I'm thinking the five 90 degree elbow fittings dont help either, only 2 are needed.

Steamhead

Do the other radiators on that system have the same size pipes?

sixplex

Depending on rad size either 1/2 iron or 3/4 iron, this is the only piped with copper. Why?

STEVEusaPA

First figure out why 'it isn’t heating too well'.
Is the pipe clogged? Low on system water? Air bound? Shut off valve issue?

hot_rod

Any idea how many btus you need?  That is how you want to size the piping

sixplex

Cleaned out a bunch of sludge from it
It's a single pipe system, air vent is on the low side of the rad, changing that, might be air bound a bit

Currently trying to figure if the repiping with a bigger pipe will have a positive impact, being a monoflow system, a pipe that is 15% smaller than designed, with unnecessary elbows makes a difference, just don't know how much of it.

sixplex

hot_rod said:

Any idea how many btus you need?  That is how you want to size the piping

Someone put that 1/2 copper in, original design was 1/2 steel which is 15% bigger, that's how many btus i need i guess

mattmia2

What kind of expansion tank does the boiler have, is it a compression tank or a diaphragm tank?

What kind of air elimination do you have at the boiler?

Given the number of questions you have about this emitter doesn't heat very well i suspect either you don't have a circulator with enough flow on the monoflow loop or your air elimination isn't very good or both.

ChrisJ

sixplex said:

Any idea how many btus you need?  That is how you want to size the piping

Someone put that 1/2 copper in, original design was 1/2 steel which is 15% bigger, that's how many btus i need i guess

I've never heard of copper pipe having a smaller ID than steel / iron pipe?

1/2" copper pipe is slightly larger than 1/2" ID.  Especially type M.

mattmia2

Oh, and that baseboard is going to have far more resistance to flow than the original standing cast iron radiator did.

EBEBRATT-Ed

@sixplex

You need to find out the btus of the radiation. That is how you size the pipe. Measure the length of the baseboard. 1/2" copper will carry 1.5 gpm which equals 15000 btu. Your baseboard does not likely need that many btus.

The pipe size and material is probably not the problem and replacing it with 3/4" probably will not help. If it is a 1 pipe Monoflo system, you need two Monoflo tees one on the supply and one on the return and it needs to be piped right.

Its probably copper because it was an addition to the original system and maybe it was not installed right

mattmia2

The baseboard will also heat and cool much faster than the standing cast iron radiators so while the areas with the original radiators are still heating the areas they are in with their residual heat, this area will have stopped heating so you likely will not be able to balance this area with the rest of the system, especially since it is monflow.

sixplex

mattmia2 said:

The baseboard will also heat and cool much faster than the standing cast iron radiators so while the areas with the original radiators are still heating the areas they are in with their residual heat, this area will have stopped heating so you likely will not be able to balance this area with the rest of the system, especially since it is monflow.

This radiator is the same all the the others in the system, cast iron baseboard type

sixplex

ChrisJ said:

sixplex said:

hot_rod said:

Any idea how many btus you need?  That is how you want to size the piping

Someone put that 1/2 copper in, original design was 1/2 steel which is 15% bigger, that's how many btus i need i guess

I've never heard of copper pipe having a smaller ID than steel / iron pipe?

1/2" copper pipe is slightly larger than 1/2" ID.  Especially type M.





1/2 copper ID 0.569 for M, 0.545 for L.
1/2 iron schedule 40 (seems to be the most common) ID .622
So the copper has 12.37% smaller ID than the iron.
I visually compared at the home depot, seems about right

1/2 iron seems to be equal to 5/8 copper (id) but 5/8 ID copper isn't a thing in canada, only 3/4

hot_rod

1/2” copper almost fits inside 1/2” schedule 40 pipe, so it is a smaller OD and ID

Same with 3/4, that is how urinal nipples work and some tub spouts

mattmia2

sixplex said:

mattmia2 said:

The baseboard will also heat and cool much faster than the standing cast iron radiators so while the areas with the original radiators are still heating the areas they are in with their residual heat, this area will have stopped heating so you likely will not be able to balance this area with the rest of the system, especially since it is monflow.

This radiator is the same all the the others in the system, cast iron baseboard type

Are your posts about the emitters that don't heat about a different system? Or are those the only standing cast iron radiators on the system?

sixplex

It's a small apartment building 6 units, all apartments have cast iron baseboard rads, and there are 3 free standing rads in the common hallway, 1 of which doesnt heat at all. The one that doesn't heat is on a different return than the rad in this thread they arent related

mattmia2

So the cast iron radiators are on a separate thermostat from the baseboard?

sixplex

They are all cast iron. Baseboard ones are cast iron too. The free standing one that doesn't work is on a separate thermostat from the baseboard cast iron in this thread

mattmia2

They are all cast iron but the ci baseboard has a lot less mass than the standing ci so if they were all run off a t-stat sensing the temp in a room where there was ci baseboard it probably wouldn't run long enough cycles for the standing ci to heat, but they are separate t-stats so that isn't part of your problem.

Rich_49

IF i could interject with a question ? In all the years I've been doing this and my descendants before me , I cannot recall ever seeing either baseboard ( copper or Cast ) or radiators that were sized for anything other than 1 gpm . Temps vary for sure but always 1 gpm . 1/2 copper should be sufficient correct ?

hot_rod

I would  guess 1/2” system's are flowing 1- 1-1/2 gpm. It depends on what the circulator is capable of and the head of the circuit

most all baseboard outputs charts show 1 and 4 gpm 

Rich_49

hot_rod said:

I would  guess 1/2” system's are flowing 1- 1-1/2 gpm. It depends on what the circulator is capable of and the head of the circuit

most all baseboard outputs charts show 1 and 4 gpm 

With a disclaimer about guaranteeing 4 gpm and if that cannot be guaranteed you must use 1 gpm . Did not Siggy say using the extra power and such to have such a minimal gain in output was never truly worth it , or something to that effect ? Maybe that was just on the Mastering Hydronic Design courses .

hot_rod

Rich_49 said:

hot_rod said:

I would  guess 1/2” system's are flowing 1- 1-1/2 gpm. It depends on what the circulator is capable of and the head of the circuit

most all baseboard outputs charts show 1 and 4 gpm 

With a disclaimer about guaranteeing 4 gpm and if that cannot be guaranteed you must use 1 gpm . Did not Siggy say using the extra power and such to have such a minimal gain in output was never truly worth it , or something to that effect ? Maybe that was just on the Mastering Hydronic Design courses .

Use higher flow rates, above 1 gpm all the way to 4 gpm, if for some under-designed reason the 1 gpm is not meeting the load. It's the number they tested and certified to at IBR, once upon a time. I'm not sure who chose it or why?

With todays ECM 100- 120W would move plenty of flow if you had to run higher gpm for extra output.

4 gpm, if you need to run that much flow in a 3/4" circuit is still in a comfortable flow velocity.

I'm not suggesting you design around 4 gpm, the number is shown in most all radiation charts as a guide to what you get and what it cost in additional pump requirement. Certainly flow rates between 1 and 4 could be considered it's not one or the other.