Puzzle: Two Solutions for a Hydronic Systems Flow Problem- Which is Best?

adriennet

Hello Heating Help:

I'm a Philadelphia-area homeowner who needs help with interpreting conflicting advice I have received from two respected heating companies. Both of them suggested posting here to get your feedback.

Issue

-As part of a home renovation, a 30’ length of main heating pipe serving most of radiators in the house was replaced to create increased basement ceiling height. The pipe size was changed from the prior 3" steel to 1" oxygen barrier PEX for the full 30’ run to the rear of the house. An existing run of 3” pipe serving the front of the house was not changed.

-Now, when the controlling valve is set at 45 degree angle for even distribution of water to the front and rear of the house, we have no heat reaching the 3rd floor rear radiators, no heat to the farthest rear radiators in the kitchen and basement, and also only tepid heat to rear 2nd floor radiators.When flow is cut to the front of the house and fully pushed to the rear, we only have very faint levels of heat in the rear third floor and still no heat in basement rear radiator.

Two heating companies have both diagnosed the problem as a flow issue but have opposite/different solutions, which hopefully I captured correctly here:

Company 1: Their thinking is that the issue is that there is not enough volume of water going to the rear side to carry enough BTUs to the farthest rear radiators especially for single-digit cold weather so main pipe size needs to be increased.

Scope:

Remove 1” PEX main and re-pipe the supply and return mains in the basement with 1.25" copper

Install 1.25” ball valve on forward supply main in order to better balance flow from front to rear of home;

OK to leave 3" serving the front of the house. [Optional: re-pipe the aluminum kitchen rad to its own loop; rad appears to have been oversized to account for aluminum differences]. He noted that the existing new connections are also reducing the 1” PEX to ¾” effective flow - how important is this.

Company 2:

Their reasoning is that since flow to the 3” side is currently better, the home is not heating evenly. Their thinking is that the flow to the whole system needs to be similar pipe size and 1" PEX will be OK to carry enough BTU's.

Scope:

Re-pipe the existing 20’ of 3” pipe in the boiler room with 1.25" copper pipe to equalize the system;

Connect new front main 1.25” pipe to the now existing 1” PEX rear mains. (Leave 1” PEX as is)

Re-pipe the kitchen rad with .5” PEX to create its own zone.

I’d like a solution for heating comfort and also cost efficiency.

Here’s more about the system:
• Hydronic system with a Buderus boiler (G115WS/3)
• Oil fired
• 1-1/4" pipe coming out of the boiler.
• Grundfos Pump UPS 15 58 PC
• All cast iron radiators, except large aluminum rad in kitchen
• Photos of boiler, pump, piping and house floor plan attached.

House layout:
The house is an old Philadelphia "twin" (ie duplex with a party wall). My side's floorplan is a skinny rectangle, 14' wide x 56' long, 4 stories tall if the partially walkout basement is included as a story.

The boiler room is at the front of house on the basement level. Two main branches come off the boiler – one shorter (8’) main to the front of the house (controlling 5 rads) and one 30’ Bmain to the rear that serves the rest. (Note: Final 8’ of main is now above drywall ceiling)
Please let me know if I’ve left out any important information or if a video would help.

Thank you so much for your help sorting through what would be the best solution.

Photos are:

Boiler Front View; Boiler from L side; Boiler from R side;Boiler Info; Overall Boiler Room view; Pipes to Front; Pipes to Rear into last 8' under dryway; Pipes to rear from Boiler room; Main Valve and Pump

A- House Floor Plan.pdf

Ironman

Water takes the path of least resistance. The old piping was sized for gravity flow. You can’t re-size part of it for forced flow and expect it to work.

You MAY be able to split the loops and add a separate circulator for the restricted loop, but no guarantees on how well that will perform.

bjohnhy

Did the 2nd and 3rd floor radiators heat well prior to the pipe change?

leonz

I hate to see old reliable gravity heating systems butchered like that.

The other no no is cutting holes in the full dimention 2" by 12" joists

because it weakens them. The joists look like Hemlock wood. 😓

hot_rod

I think a balance valve in each of the supplies would allow you to tune it in. Any idea how many gpm you need to move to the radiators?

Always consult a joist drill chart when drilling structural joists. Seems odd with all the other stuff under the joist that they were drilled? Could have boxed them in along the waste piping if the ceiling is to be finished.

Screenshot 2025-01-26 at 1.55.49 PM.png

LRCCBJ

Fire both of the companies. All they want to do is spend money needlessly.

All you need to do is to slow the flow in the 3" piping to the front of the building so it matches the flow in the 1" pex going to the rear of the building.

How do you do that?

You install a 3" butterfly valve in the 3" piping ( a bit of a task) and you close the butterfly valve until you get the performance at the rear of the building.

The alternative is a second zone. As @Ironman mentioned……….one zone for the front of the building. One zone to the rear of the building. You'll need another pump and proper controls.

leonz

Your system will end up being red tagged due to the hot water heater flue pipe sharing the same chimney as the boiler.

jesmed1

https://forum.heatinghelp.com/discussion/comment/1838191#Comment_1838191

Not necessarily. Natural gas flue can share the same chimney as an oil boiler. Ours does too. However, the natural gas flue has to enter the chimney higher than the oil boiler flue. @EdTheHeaterMan just showed that to someone else in a different thread.

The photo here shows the natural gas flue entering just slightly higher than the boiler flue, but maybe not high enough. If too low, it could be corrected by re-doing the entry into the chimney so it enters higher.

Ironman

It also appears that they used non barrier pex which will allow O2 ingress and cause the iron and steel components of the system to rust out. That will also cause sludge to buildup in the the system.

Whoever did this is liable for the errors to the system and structure.

EBEBRATT-Ed

I don't think I would trust either contractor.

Typical slam it in job and when it doesn't work ….retreat.

Trying to reengineer something that is butchered is difficult and becomes a lot of trial and error.

hot_rod

It looks like some balancing is being done on this circuit? A valve on every circuit may be needed to get the whole system in balance. A 1" valve should be plenty on any of the branched to balance. I doubt you need a 3" valve anywhere?

Screenshot 2025-01-27 at 9.42.19 AM.png