Old gravity fed boiler

JUGHNE

But you would still bring new PEX from each rad to the boiler room?

Paul48

The ready-made manifolds are pricey, but they do offer a lot of features.

Jsbeckton

I was actually leaning towards maintaining the direct return (with 1” or 1.5” fostapex) rather than converting to a home run because there are about 20 rads which means I’d have to run 40 lines through a block wall that separates my boiler room from the rest of the house. Is there a significant advantage that should make me rethink that?

Jsbeckton

Other issue is that this is pretty much the worst time for me to be doing this with temps dropping by the day. Would a pro be able to swap out the steel pipe for fostapex for 20 rads in just one day so I don’t have to go without heat?

I was thinking that if the lines were all pre run then the actually swap and rad connections might be possible in one day but maybe not?

Jsbeckton

Any thoughts on downtime for a pro to swap out the steel pipes?

leonz

$$$$$$$$$$$$$$$$$

Brewbeer

This is the kind of project that really should wait until heating season is over. During heating season, the need to get the heat back on ASAP has the high chance of resulting in unacceptable compromises.

Gordy

I agree with @Brewbeer. Murphy’s law will raise its ugly head about the time the system is drained, and taken apart.

Home run to a manifold with flow meters, and I like trvs. Gives control to each rad,eliminates thermostats. A project for summer when time is not of the essence.

Ironman

Jsbeckton said:

Other issue is that this is pretty much the worst time for me to be doing this with temps dropping by the day. Would a pro be able to swap out the steel pipe for fostapex for 20 rads in just one day so I don’t have to go without heat?



I was thinking that if the lines were all pre run then the actually swap and rad connections might be possible in one day but maybe not?

One day? Probably more like one week.

We're doing this very thing on a system with 16 rad's and that's what it's taken us. We did move some of the rad's and had 4 new total runs, but no way close to happening in a day.

Jsbeckton

Wow a week! Is That even if you had the mains all pre run and the pex adapters all ready to screw on to the steel pipe?

I was thinking that the actual swap would take maybe a man hour per rad since there are easily accessible unions. There are only 10 rads on the steel pipe so with two guys it seems doable but maybe not. I understand that there is per-work and post-work but just want to limit the actual time w/o heat.

Brewbeer

Yes, some of the work could be done while the heat is still on, like installing manifolds and pulling PEX from the manifolds to the locations of each of the risers. But disassembling and reconnecting 20 risers, AND removing and installing a new boiler in one day seems fraught with potential snags. A 100+ year old gravity system isn't going to come apart without fighting and complaining, and possible breaking in a spot or two.

@Gordy 's suggestion that you home run each radiator with PEX to a manifold is a good one. If you do try to pull this off mid heating season, with the home run method, you could probably get most of the radiators up and running and deal with any problem radiators on subsequent days. If you try to zone or manifold radiators to common mains, you could end up being heatless for longer than desirable or end up with undesirable compromises.

A home run system will also provide superior adjustability and comfort vs. a zoned system.

Can you post some photos of the piping where the risers are connected ?

Jsbeckton

Photo

Jsbeckton

The 2.5” pipes go through a brick foundation wall. It would be a mess trying to get 40 all the lines I would need for a home run system so I was thinking 2-3 zones with zone valves.

Harvey Ramer

I've faced bigger obstacles than that concrete wall. I wouldn't let that deter me from doing it the best way. Hire someone to come out and punch a few holes through it so you can run your pipe.

Gordy

That’s why they make core drills, and hammer drills. Piece of cake.

JUGHNE

There have been some recent posts of systems that have been sorta/kinda zoned differently from the original gravity piping and ended up in the heating hell section.
IIWM I would connect each rad to a manifold and have the ability to adjust flow to each.
You can have manifolds remote from the boiler room, you don't have to bring every tail to one location.
You could have a manifold for each zone with a Tstat control for that manifold. Endless possibilities.
But you need someone on site who is familiar with all this. IMO

Jsbeckton

What is the advantage of a home run over a few zones with a direct return if the rads themselves already have balancing valves or I added them to the risers?

I can certainly get through that wall, just want to make sure that it’s going to have some kind of benefit. Those of you that are drilling cores, are you reinforcing the holes you drilled or just banking on them not interfering with the integrity of the wall? The current system has pipes that were cemented into the wall and now the steel runs through those pipes so there is no compromise of the wall.

Brewbeer

The sleeve around the existing mains isn't there to reinforce the wall, it's there to keep the mains from contacting the concrete, which would cause corrosion. If the wall is concrete or concrete block, a couple of 6 inch cores shouldn't make a difference, but if you post another photo of the wall further back also showing the framing above we could get a better look.

The advantage of the home run vs zoned system is that the home run system will definitely wok and work well if sized correctly.

Paul48

Are you an engineer?

Brewbeer

I'm a geologist and partner in an engineering firm and one of our specialties is foundation design and failure assessment.

Paul48

Cool..........Over the years, I've seen rather large holes put in foundations(residential), and years later there is no sign that the structural integrity has been compromised. I was just wondering if boring some holes would actually hurt the integrity. I feel that sleeving the holes is probably more for aesthetics than anything else. I understand there is reasons why you really don't want to do it. Especially, an exterior foundation. But I believe he is talking about one that is no longer exterior.

Jsbeckton

> @Paul48 said:
> Are you an engineer?

I actually am and have seen people compromise structural components all the time cutting out holes for pipes and ducts which is why I asked.

There is not much room on this side

Jsbeckton

Photo

Jsbeckton

I actually am a mechanical engineer and I’d be less worried about cutting holes if this were part of a larger wall but it’s a small section next to a doorway. There is 2 stories of brick stacked above this.

Gordy

when We say home run your radiators it does not mean that all the individual rad lines need to come back to the boiler area.

Remote manifolds are your friend. You pipe supply, and returns to the manifold.

With the wall in question how many rads are on the side away from boiler location?

Gordy

Jsbeckton said:

I actually am a mechanical engineer and I’d be less worried about cutting holes if this were part of a larger wall but it’s a small section next to a doorway. There is 2 stories of brick stacked above this.

Take a look at above the door. Look what is holding up two stories of brick there.

Gordy

Depending on information you give. The pipe that runs through the wall now could be removed, and the sleeve holes used for smaller supply, and return piping to a remote manifold for the rads.

Robert_25

Jsbeckton said:

I was actually leaning towards maintaining the direct return (with 1” or 1.5” fostapex) rather than converting to a home run because there are about 20 rads which means I’d have to run 40 lines through a block wall that separates my boiler room from the rest of the house. Is there a significant advantage that should make me rethink that?

Why not just run some 1.25" pipe though the wall, and put your manifolds on the other side ?

Brewbeer

Looks like there is a beam on the other side of that short wall segment right of the door. Reusing the existing main holes with remote manifolds seems like a good option.

Ironman

Jsbeckton said:

Wow a week! Is That even if you had the mains all pre run and the pex adapters all ready to screw on to the steel pipe?



I was thinking that the actual swap would take maybe a man hour per rad since there are easily accessible unions. There are only 10 rads on the steel pipe so with two guys it seems doable but maybe not. I understand that there is per-work and post-work but just want to limit the actual time w/o heat.

Look at this job where I just posted some more pics:

https://forum.heatinghelp.com/discussion/163504/gravity-system-boiler-replacement#latest

Gordy

Until we know what the needs are for piping to the rads in question which would dictate the size of the supply, and return to a remote manifold no need to worry about this wall.

I can safely say you won't need that size existing pipe now. So use the sleeves. Those sleeves wer put in after a hole was made, and patched around them.

To the OP want to see a nice home run install view this thread https://forum.heatinghelp.com/discussion/163504/gravity-system-boiler-replacement#latest

Ironman

Gordy said:

Until we know what the needs are for piping to the rads in question which would dictate the size of the supply, and return to a remote manifold no need to worry about this wall.

I can safely say you won't need that size existing pipe now. So use the sleeves. Those sleeves wer put in after a hole was made, and patched around them.

To the OP want to see a nice home run install view this thread https://forum.heatinghelp.com/discussion/163504/gravity-system-boiler-replacement#latest

@Gordy
Great minds think alike.

Jsbeckton

> Why not just run some 1.25" pipe though the wall, and put your manifolds on the other side ?

The other side of that wall will be finished.

Jsbeckton

> @Gordy said:
> when We say home run your radiators it does not mean that all the individual rad lines need to come back to the boiler area.
>
> Remote manifolds are your friend. You pipe supply, and returns to the manifold.
>
> With the wall in question how many rads are on the side away from boiler location?

There are 8 rads down that side.

Jsbeckton

> @Gordy said:
> Until we know what the needs are for piping to the rads in question which would dictate the size of the supply, and return to a remote manifold no need to worry about this wall.
>
> I can safely say you won't need that size existing pipe now. So use the sleeves. Those sleeves wer put in after a hole was made, and patched around them.
>
> To the OP want to see a nice home run install view this thread https://forum.heatinghelp.com/discussion/163504/gravity-system-boiler-replacement#latest

Ok, I know the room loss so would the next step be to calculate the flow rates needed for each rad? I have some in wall rads as well as baseboard. Is there a good resource that shows the heat output of various types of rads for different flow rates?

If I can get this done then it just seems a matter of determining the flow rate needed to each zone so I can determine the size of the mains I need.

Jsbeckton

I did look at that other thread, nice work!

Does a home run setup mean that I need a circ pump on each manifold? I was originally thinking one variable speed pump and zone valves.

Gordy

Going to need the heatloss of the rooms. The type of CI rad (thin tube, column) so you can calculate the EDR (equivalent direct radiation) of the radiator supplying the rooms load. Type of baseboard, and how many feet supplying the load in those associated rooms. There are output charts available at different water temps.

Then you can figure out the tube size supplying the rad, or baseboard, the flow rates. Then you size the circulator.

The EDR survey also lets you see what water temps you will need at design day. Whether or not radiation is balanced to the loads. In other words will an average water temperature of 160 be sufficient to meet the load in all radiated areas.

Gordy

Take pics of rads, and baseboard we can help you decipher types.

Ironman

Jsbeckton said:

I did look at that other thread, nice work!



Does a home run setup mean that I need a circ pump on each manifold? I was originally thinking one variable speed pump and zone valves.

It may be possible to use one circ, but we need the info requested to determine that.

I used two circs on that job because the owner wanted two zones. The risers from the gravity system were intentionally smaller for the upstairs to force more water to the downstairs rad's. Pumping the system causes the opposite effect: water flow wants to go to the downstairs rad's because there's less resistance to flow. Using separate circs eliminated the issue, though it may have been possible to do with the flow setters.

Jsbeckton

Here are some photos of the different types of rads I have.