Hydronic heat, I broke it.

[widefat]

Throw out some ideas - nothing is too simple; talk to me like I am 5 years old.

It is a one pipe main system.
Two zones
I believe the pressure differential is 6lbs.

Everything worked until I messed with it.

The problem -
Water is not flowing through one section of radiators.
At each end of the feed, the main pipe is hot.
The changes - along one wall, I had one long radiator. I added a door in the middle of the wall.
To accommodate the door, I cut a section out of the radiator.
I dropped a section of pipe down underneath the doorway , through the crawlspace, and back up to the other side of the door.

I attached a drawing - note the pipe sizes.
Also note that now the water will not flow at all, from the beginning of the pic to the end, even through the unmodded radiator
So why wont water flow now?

 

[oosik]

Sooo.... the top pic is the system down one wall - bottom picture is down the other wall. My guess is an air block somewhere in the system. Is there a valve somewhere that was accidentally closed. What about the circulating pump - is it still OK.

 

[widefat]

Sooo.... the top pic is the system down one wall - bottom picture is down the other wall. My guess is an air block somewhere in the system. Is there a valve somewhere that was accidentally closed. What about the circulating pump - is it still OK.

I changed the pic - the pic shows the radiators before and after my changes.
The circulating pump still supplies the rest of the house fine.

 

[gsganzer]

Is the air bleed valve on each side at the high point and have you bled them sufficiently? It looks like you've created a "P-trap" and this is most likely your problem preventing flow. One of our TBN resident plumbing guru's will be along shortly to give us the "skinny".

 

[CobyRupert]

Which way does it flow?
Shot in the dark here, but did you changes change the way it needs to be bled?

 

[nybirdman]

Vents on the drop and rise;air block for sure.

 

[the old grind]

If you're showing one leg vs all of the system, we have net flow through a 1/2" pipe that has just had four 90s added to it.

If this is a 'branch', then the extra turns are adding that much to flow restriction to it. If this were a hydraulic circuit, a flow divider would be indicated.

An extra circulating pump can be added to a branch, but while it might improve flow in the portion shown it might then deprive other areas.

What are/were we using for zone control already? IMO, 6 psi PD should push air out unless flow rate is too slow.

Inquiring minds might want to see a flow chart of the whole installation for perspective.

btw, "radiator-free" for 15 + yrs, and I don't miss the dusty fins, air bubbles, expansion tank, hassle to vacuum around, or boiler maintenance. (nat gas)

 

[LouNY]

A couple of questions;

You say the rest of the house is still working off the circulator,
is it a single circulator with multiple loops?

You may be able to get away with adding a bleeder at the end of the trap you created,
that would be on the left hand side of the right most radiator in your drawing.

Many times with one circulator on multiple loops they will require balancing valves to achieve the proper flows.
Restricting the flow to the easiest flowing to push the flow through the more restrictive loop.

Also depending on who and how your system was set up it was not unusual for the circulator to be pulling thru the system and pushing back into the boiler.
This type works well but is easy to airlock.

When you state a 6 pound pressure differential is that a differential in the system or 6 pounds overall, my auto fill maintains almost 15 psi in the system.
To see the differential from the circulator would require a differential pressure gauge or 2 gauges one on each side of the circulator.

 

[DerbyRunner]

I agree with Old Grind and Lou. The system probably needs a bleed at the high spot where it comes up from the crawl space. In the p-trap you created.

And, adding four 90 degree elbows added a flow restriction to this circuit that is not present in others. So you might need to balance this circuit with the other. Maybe an easy way to do that is to add a gate valve to the other circuit. Slowly close it until both systems have equal flow.

 

[the old grind]

Since a stalled or blocked (centrifugal!) pump sees less resistance and does less work (hear your shop vac freewheel and rev up when blocked?) there is no harm, hassle or waste by adding individual pumps to flow-restricted branches to aid flow and/or purging.

My hydronic system (1800 sq ft home) was replaced with forced air and I saved the Taco circulating pump, a whopping 1/25 hp that at most would draw .70 amps at 120v.

(.7 a = >1k hour run time per kw used, ~ $.15 here)