Help me understand my hydronic heating system - air lock?

webhead

Hey all - have read a few posts about hydronic heating systems on here, and it sounds like there are some experts in here willing to help!

Below you'll find photos of mine. It was in the home when I purchased it and moved in, so my familiarity is minimal. I believe it was installed in 2004 when a renovation was done.

The main pump, an Armstrong, was replaced last year by yours truly as the old one failed. Up to that point, no issues with the system at all. Changing the pump has kept it humming along happily as well until just recently.

One of the zones suddenly is no longer getting heat to it. The thermostat has been checked, it works, and the Honeywell valve actuator on the pipe seems to be functioning as well. Pulling it off and manually turning the valve open/closed, everything seems fine.

The zone in question is the one closest to the photographer in the image, with the blue faucet, which appears to have been added on at some time based on the additional brazing done there.

Looking at what we have here, can anyone guide me on how to purge that zone, as I'm reading that it likely has an airlock?

Thanks in advance! If you are able to help and guide me, and happen to be in the Lower Mainland of Vancouver, DM me and I'll get you a gift card to my brewery as thanks!

hot_rod

With the thermostat turned up, do you have 24V AC at that zone valve. If you do, you should see the lever on the end move open, or hear the motor.
Or remove the cover and see if the gears turn inside. If not the actuator is bad.

I don't see any type of auto air purger on the system, so manual purging, or bleeders out in the system are the only option?

webhead

I have verified that the valve actuator is not the issue. It responds as expected when thermostat is cranked up it opens, and set colder than air temp it turns off. 

How do I manually purge this is the question?

Big Ed_4

You have a parallel system piped direct return , it should be piped reverse return . To correct your problem , repipe one of the supplies to the opposite side of the manifold .

For better understanding , search the site....

webhead

It has not been an issue for 20 years the way it’s setup….maybe my photos are missing something that shows why it works as it is?

hot_rod

Turn the yellow handle ball valve below the zone valve off, hook a hose to the hose valve above it, manually lock the zone valve open and purge away.

Looks like a fill valve hiding here. Make sure it doesn't have any shut off valves upstream.

There may be a lever on it, if you lift the lever the valve fast fills. But watch the pressure gauge, if you go over 30 psi the relief valve will pop open and make a mess.

So purge with an eye on the pressure gauge.

Purge into a 5 gallon bucket to see when the air bubbles stop. A 5' washing machine hose works well for purging.

If nothing comes out, after you open the purge valve for a minute, you could have a frozen line?

webhead

Interesting....I did exactly this procedure (and closed all the other ball valves, yellow levers, for the other zones to isolate the problem zone) and nothing came out...so, maybe frozen line indeed? It has gotten very cold here in the past couple of days. Efff

hot_rod

Are those old Honeywell valves?
In some rare cases the ball comes off inside those brands of zone valves and closes off the opening.

We had a call last year where zone valves inside baseboard heat, inside the condo froze! So it is that time of year.

webhead

How the heck do I get that open to inspect?! I have replaced the Honeywell actuator of the valve on the zone in question, and verified it's functioned properly, so it could be the mechanical valve itself.

I do doubt that I have a frozen line as it is all indoors...

hot_rod

I have also seen the washer in this boiler drains stick close, pull iff the bib screw

It can happen if you flow backwards through a boiler drain also. Does any water at all come out if the purge valve,

is there pressure in the boiler ? Is the fill valve opening?

webhead

All other zones are hot. Boiler doesn’t seem to be an issue. 

webhead

With this blue valve open, yellow closed and all other yellow open, no water comes out.
 
The Honeywell valve is open as best I can tell, unless the ball has fallen off inside as you suggest hot_rod. Is it possible to open them up while installed on the pipe?

webhead

PS is this not the automatic air bleed?

webhead

Boiler readings:

hot_rod

But you get water under pressure from  all the other purge valves?

You getting down to some surgery.

The yellow ball valve will isolate one side. I have been able to kink off pex enough to stop flow if you want to try that above the zone valve

On 1/2 pex you can use a vice grip pinch tool, or build one with a larger vice grip and  two round objects

Or drain down the system to that level

Yes the zone valve comes apart, don’t lose the screws some are special  design

webhead

Since this pex is 20 years old, I worry about pinching it and it surviving.... if I close all yellow ball valves, would I only then end up draining the water in the zone I'm working on?

Really appreciate the help here! I consider myself relatively mechanically inclined, just never dealt with something like this before!

hot_rod

Yes its s risk pinching pex.

Since the zone you want to work on will not drain, you will be draining from another zone or the bottom of the boiler to get the pressure to zero to work on the problem zone.

Unless there is another valve in the pex  above the zone valve

worse case you repurge all the zones once you get the fix.

webhead

Ahh, gotcha. Cheers.

hot_rod

I don't see any air purger. The round brass vent you have is for catching air that rises up to a high point in the piping. A float type air vent. It doesn't pull air from the moving flow coming out of the boiler. There are vertical type air purgers that would go into the line below the supply ball valves, the outlet of the boiler.

The best place to eliminate air is the hottest point in the system, close to the boiler. Point A on this graph.

If you are draining the boiler, you could add one. Press type go into a line in seconds if you can get a press tool.

If all those other old HW zone valves are staying, add a pex ball valve above them. They are all going to fail at some point

webhead

Variation of your tool recommendation. 

Got the valve apart, all seems ok inside.

Unfortunately (cause I like living life dangerously) I released the vice grips slowly to see if any water would come through. Nothing! ****!? All yellow handled ball valves open. Hmm. 

hot_rod

Good job on the pinch plier hack.
Is this an upstairs zone. Could it be you don’t have adequate fill pressure. Those dual gauges are not always so accurate. Bump the fill pressure. 5 psi or so for a test. Or screw a pressure test gauge on one of the other purge valve to confirm pressure

webhead

I am now thinking it is in fact frozen. 

A bit more background; this zone feeds some fins on a fresh air return that my wife has been running nonstop for literally months now for reasons we won’t get into. 

As it has now gotten really cold over the past few days here, and I have smart thermostats, my guess is that the schedule set by them turned off the call for heat one cold night, the fan kept blowing icy cold air over the fins for 8+ hours, and it’s now blocked frozen. 

So I’m trying this:

webhead

I have everything set to purge that zone and am watching for water. Ha!

Cheers for the pincher grip props. Hockey tape for grip. 

GW

you're sure it's not a freeze?

If it's crazy cold, and If the zone was off for a while, and the piping routes are not ideal, you will freeze a zone.

webhead

Gary, see previous post with hair dryer…though it’s now been replaced with a space heater. 

webhead

Update: confirmed to be frozen as water just hit the floor around the air return fins. Hoping just that “rad” is what’s frozen and blown. Ugh. 

GW

Hmm OK you must be in a different time zone, your post jumped my post.
Water hit the floor, is that a good thing or bad thing? Your coil froze up and burst? You are getting water into the bucket at the boiler? Anyways, sounds like your figuring things out.

hot_rod

If it is piped with Pex tubing, usually that can handle some freezing.

webhead

Coil froze and burst. 

New coil ordered and I just verified no other issues in the loop by simply closing it as shown below and opening everything up. 

Should be back in business by Wednesday. New coil arrives Tuesday at who know what time. 

webhead

If anyone is still following along, and wondering why no update; the weather here has delayed all deliveries, so the coil has not yet arrived. Dang it.

hot_rod

So cold air from an attic just falls down through that coil? Does that loop stay hot all the time?

webhead

This is actually in the basement. There is a fan that turns on when the exhaust hood in our kitchen enabled to ensure we don't get negative air pressure and blow out the flames on the range.

The range is ridiculous, it's a full blown commercial grade setup, way beyond what we need. Was in the home when we moved in.

The loop did not stay hot all the time, hence it freezing...but I have rectified that by adding a thermostat right at the coil outlet. Now, should the air coming through be colder than 10C, the loop is made active.

hot_rod

Smart of you to think about make up air.

webhead

Oh, I can't take credit for that. The previous homeowner was the smart one, but they didn't hook up the thermostat by the air return for whatever reason so that coil never got hot.

Until recently, wasn't a big deal, but the wife decided in the past while to have it on all the time (even on low) which got it cold af in the basement. So I wired it in with the basement smart thermostat...and that is why we are here.

hot_rod

The old expression with make up air or economizers, if you need it you heat it.

webhead

HA! Yup! Can't wait for the coil to arrive to finish this up.

webhead

Annnnnd we’re baaack!!! New coil installed, heat is on. 

Wired in a dedicated thermostat for that zone so it won’t turn off via the smart one at night / on a schedule anymore. If it’s cold, turn on. No more freezing!!