Home Run vs. "Stacked" Home Run for 3 Storey Home

HydronicRookie

Hi there,



I'm making my way through John Siegenthaler's book and I'm trying to decide on whether a "Stacked" Home Run distribution is preferable for a 3-storey home as he suggests it might be. By stacked, he's referring to manifolds being housed on each floor, each supplied by a single riser; this in contrast to all the manifolds being housed in the boiler room with all the PEX being routed to their respective floors from the basement.



Are there additional benefits other than saving on PEX tubing, and saving the heat that would otherwise be lost in transit from the basement up to the second and third floor?



I've only got 3 rads on the third floor, so I'm unsure whether its worth what I imagine would be extra work and planning.



Thanks!

Eastman

I would expect

one to downsize tubing and manifold diameters if possible.



So maybe one could use something like a wirsbo junior manifold.



And of course smaller pex is easier to work with.



Generally, distributing the manifolds avoids having huge unmanageable bundles of pex coming together at one spot blowing out all the studs. Even 3 rads requires 6 runs of fairly large outside diameter tubing. (The stated diameter is for the inside --1/2 inch is more like 3/4 inch, requiring an even bigger hole.)



But if you're using the existing rads in place, perhaps it's best to using the piping layout that was originally employed?

Mark Eatherton

Why a manifold...

Why not just pipe it like the deadmen did with a parallel reverse return piping network. Size the pipes to carry the connected loads, down sizing as loads drop off the supply main and increase as they flow back into the return main.



Manifolds do have their place, but on a three radiator system, I'd just pipe it in parallel reverse return and be done with it.



ME

Gordy

Mark

+1 manifolds have thier placethats not one of them.



Edit: Sometimes we try to apply technology to everything we do. Not all bad, but dont forget the heritage behind inovation sometimes the old way is better, cheaper, and easier.

HydronicRookie

Clarification

Great to hear from you all so soon.



I should mention that the old cast-iron piping has mostly been dismantled, though we're keeping the rads in place.



Mark and Gordy, are you saying I shouldn't implement a home-run system at all? And that running pex from a manifold with balancing valves on the other two floors is inferior to reverse-return in the whole house? Or that I should do reverse-return only on the 3rd floor seeing as there are only 3 rads up there.



Eastman, point taken about the outside diameter of these 1/2" pipes. Have you installed a "stacked" home-run before - were there any 'gotchas'?

Gordy

Lack of information

So how many rads on second floor?



Something to consider if you are using a local chase for your stacked manifolds. How many runs of pex, and supply return piping to each floor manifold. Piping size to deliver required btus to each floor for the manifolds. Piping size to deliver required btus to each rad.

Mark Eatherton

You can run it however you want...

so long as you DON'T pipe it in series.



Home running = 6 PEX runs 12 PEX connections.



Parallel reverse return = 2 PEX runs (differing sizes) with 6 connections (excluding tight radius turns requiring 90 degree els).



If you don't value your time, and have a lot of excess 1/2" tubing laying about, and like spending money on manifolds, and having to find a decent accessible location for them, then home run it.



If you value your time, run it parallel reverse return, and you can still install non electric TRV's on each radiator, and use a smart pump to move the fluid.



Just because a respected author shows a manifolded home run system doesn't always mean it's the best way to run the installation. Probably good for DIYer that doesn't have piping skills or can't do the associated /required math, but not for everyone or every job. It's just another way to do the piping. Quite material intensive as well, and if you are trying to be competitive, then you need to look at and understand ALL piping options..



GIve the radiator sizes (in square feet of EDR), the connected load (doubtful the load and EDR will match) and the proposed routing, and we can help you size your piping system.



I cut my teeth on parallel reverse and direct return piping. Reverse return piping on cast iron radiators is self balancing. No balance cocks required for each branch, especially if you use non electric TRV's.



ME

icesailor

Less Pipe:

Parallel reverse return rocks. If you find something that doesn't work and change it to parallel reverse return. it will (almost) always work.

And far better than manifolds with home runs that are connected as direct returns.

First out, first back = BAD

First out, last back = GOOD.

Eastman

connections

I think ideally, it's still about the same number of connections? (12 versus 10)



But if one is using pex and varying the pipe size, the inventory list becomes quite complex. And the larger diameters toward the ends are more likely to require elbows at bends. The connections tend to be in awkward places that frustrate the inexperienced, etc... lots of reasons someone might prefer a manifold in a given situation. Not that I'm advocating one way or the other. I feel like in a retrofit one would want to do whatever method works with the least destruction. In that context, the cost of the manifolds might not be significant, or may end up lowering the cost of the project.

Eastman

gotchas

To answer your question, no i've never done anything that involved multiple remote manifolds.



In a typical home run system, the pressure drop across each heating element loop is equal. If you chop up the manifold and put part of it in different locations, the delta p drop will vary between the manifold sets. The piping out to the remote locations makes up the difference.

icesailor

Antique Thinking:

For my antique thinking, the concepts of parallel reverse return should always be considered in any piping array. If you want to use manifold blocks and make all the runs align on the supply and return, feed the supply block from one end, the return block from the other end. If you have multiple sets of blocks, feed them as parallel reverse returns. It won't ever be wrong, and might cover some problem you didn't anticipate.

If you just pipe it as a direct return (first out, first back) you might have balance problems that will drive you crazy trying to balance it out. At least with Parallel reverse return, it is self balancing to a point. Water and electricity seek the path of least resistance. When using these excessively long home runs with 1/2" PEX, you need any advantage you can get. Before you start over pumping the system worse that it already is.

JMAO

HydronicRookie

Reassuring...

Thanks for all the input regarding my situation and suggesting I consider a reverse-return design from top to bottom. The added cost, and perhaps added time associated with the use of manifolds is not insignificant to me and their usage is perhaps overkill, especially when considering to my three-rad 3rd floor. But what attracted me to it initially, was the (seeming) simplicity of installation - that i'd likely use 1/2" PEX for all runs from the manifolds, most connections would be the same (and accessible/exposed in case any of them should prove faulty), from where I could even out flow imbalances and have the flexibility to isolate zones if need be. I do fully appreciate, that flow balance could be easily designed into the system from the outset simply by employing reverse-return, but my inexperience is swaying me towards the 'dumbed-down' approach.



The 'stacked' approach would be adding a bit more complexity in design and installation, but doesn't seem overly intimidating to a novice like me, yet that is. The added benefits, especially the mentioned avoidance of crowding the basement with runs, seems to justify the added work. That being said I will heed your advice in incorporating a reverse-return approach along with the stacked manifold system where possible.



I hope to draft a design in the coming weeks, and verify that I can find good placement for the remote manifolds, for that though, I'll likely start a new thread.



Thanks again!

HydronicRookie

And I eat my words...

I just went back for a closer study of the existing chases and quickly realized that having a simple home-run distribution from the basement might, in the end, be the path of least resistance. While looking at the way the headers (2" x12" wood cross-beams) run, it occurred to me that placing a manifold on each floor would require a considerable amount of 'destruction' through headers and studs, let alone the trouble of finding an appropriate place to house each one.



I still have to count my runs and see if they'll fit in the existing spaces. I'm starting to see the appeal and economy of a reverse-return setup, as I start to count the feet of PEX that'll be required to do the job.

Eastman

what kind of layout

What was the previous piping configuration like? None of of this is all or nothing. You could have copper in the basement with a transition to pex snaking up through the floors. You could have multiple manifolds distributed around the basement. In general though, take advantage the inherent qualities of radiators. This type of system can frequently operate at a high delta t which requires low flow. And low flow favors smaller piping.

The Steam Whisperer (Formerly Boilerpro)

Look at your Pex size

It is unlikely you need 1/2 Inch pex to feed a single radiator.    Most of the time the existing radiators are so oversized, you can size at a 30F to 40F delta tee (at 140 F supply if the home has been insulated). which means very low flow rates and little pipes (easier to install and less costly material), little pumps (higher electrical efficiency) and higher efficiency if you are using a condensing boiler.  3/8 is usually all you need for a typical room.  1/4 gpm will move about 4,000 to 5,000 btu of heat.  Or if you really want small piping, install a mini-tube stem system.....the delta tee is about 140F.  3/8 copper supplies, 1/4 inch copper returns.

HydronicRookie

Previous configuration

was done in parallel direct-return, with four main parallel branches servicing:

1. 1st floor (front of house)
2. 1st + 2nd floor (back of house)
3. 2nd+ 3rd floor (front of house)
4. 3rd floor (middle of house)

So that's 3 chases I could use to feed PEX through. Still have to do the pipe calculations, but low-flow, smaller diameter PEX, and high Delta would be great.

HydronicRookie

The existing radiators

are almost all oversized, in some cases by a few thousand btu's ( calculating average water temp of 170˚F), so there's definitely room to lower the water temp. A few rooms are matched pretty evenly, so they may require an additional rad, and I'm still sourcing rads for a couple rooms that are missing them.



I hadn't considered 3/8 would even be an option, but then again I haven't yet sat down to do all the calculations. Good to know though, thanks!