How to drain a single zone in my closed loop hot water system

adk0212

> 1) You can cut where needed after bleeding off <BR>
> the pressure from the drain you described, and <BR>
> have a shop vac ready...<p>
Ah yes! For some reason I was assuming I'd sweat the fittings apart which would be impossible with water in the pipe, but I could just cut it and clean up the result. Thanks! <p>
> 2) You can leave the <BR>
> hose attached, and loosen a union on the supply <BR>
> side and blow compressed air from a compressor <BR>
> through the loop and drain it like a sprinkler <BR>
> company does it.<p>
That would be particularly nice, if only there was a union on the supply side. :( <p>
> Do you have zone valves or <BR>
> pumps for each zone? <p>
Zone valves. Here are a couple photos of the business end of the system: <a href="http://www.kroptech.com/~adk0212/pics/furnace/">http://www.kroptech.com/~adk0212/pics/furnace/</a>

Thanks for the advice!

adk0212

Draining a single zone in my closed loop hot water system

As part of a rennovation project I need to temporarily remove some baseboard fin radiators. Like an idiot, I'm doing this during the winter so I'd like minimize the likelihood of disaster by consulting the experts.

I'd like to drain only the zone that I need to open up and continue to run the boiler and remaining zone as normal. I have ball valves on both the supply and return side of each zone, so it looks easy to isolate one zone. There's also a drain spigot in the shared return line that looks like where I'd want to attach a hose to drain a zone. What's not clear is how to ensure that all the water is out of the zone since the drain is higher than most of the piping and rads in that zone. (I'm draining the basement zone and the spigot is about 3 feet off the basement floor.)

A related question is if running the system with one zone isolated but "open" (i.e. a section of pipe and baseboard missing) for a few months is likely to cause any long term harm. After the rennovation is over I plan to connect the loop together again open the zone back up for operation.

Thanks for your advice!

Timco

draining

1) You can cut where needed after bleeding off the pressure from the drain you described, and have a shop vac ready...

2) You can leave the hose attached, and loosen a union on the supply side and blow compressed air from a compressor through the loop and drain it like a sprinkler company does it.

Do you have zone valves or pumps for each zone?

Tim

adk0212

draining

> 1) You can cut where needed after bleeding off

> the pressure from the drain you described, and

> have a shop vac ready...

Ah, yes. For some silly reason I was thinking I'd sweat the fittings apart, but I could just hacksaw it and clean up the result. Thanks!

> 2) You can leave the

> hose attached, and loosen a union on the supply

> side and blow compressed air from a compressor

> through the loop and drain it like a sprinkler

> company does it.

That would be particularly nice, if only I had a union on the supply side

> Do you have zone valves or

> pumps for each zone?

I have zone valves on each zone. If fact, here are a couple photos of the business end of the system. http://www.kroptech.com/~adk0212/pics/furnace/

Timco

You can cut the line at the boiler, and still blow it out, and just sweat a coupling back on...

You will need to disable the zonevalve...or just leave that zone's t-stat off,so it does not open and try to pump and fire a closed loop.

Tim

adk0212

I may cut at the boiler as you say, since there is an air vent (I think) that looks very corroded and probably should be replaced. Photo here

I'll turn off the t-stat, and maybe even disconnect it to ensure there are no accidents. Just read the article about running a circulator pump with the zones valved off. Ouch.

Thanks again for your advice!

Timco

Do yourself a favor & change out that valve...it will just unthread.

Tim

brucewo1b

Air vent

And add a 1/8' M/F ball valve when you put the air vent back in

B.S.

EJW

Take a look at the ballvalve next to the air scoop, I think there is anti freeze in your system. I would like to see where that relief valve discharge pipe goes also. EJW

adk0212

You win the prize for most intriguing reply. I heard from the prev owner that there is antifeeze in the system, though I'd forgotten that until now. First question, how the heck did you know that from the ballvalve? Second question, does the existence of af change the course of action I should take?

The relief discharge ends just behind the water heater off the left side of the shot. There's a floor drain on the other side of the room, but it would be unpleasant if the relief blew (though not as unpleasant as if it didn't).

brucewo1b

Adam

The white stuff around the packing nut is a give away, but my guess is that it is rather weak at this point by the looks of that air vent and the pipe below it. Have the system tested to see if the af is still good if it is drain and save if not flush he whole system and re af it. AF can leak from a smaller hole than water so leaks tend to show up once a system has af installed.

B.S.

adk0212

Antifreeze

Honestly, I was thinking of not replacing the af. I don't see a compelling reason why this system needs it, but I may need education on the matter. I have emergency backup heat in the case of extended power failure. There are a couple spots where the basement piping goes thru the slab under doorways and such. Those are about the only places I'd be worried about a freeze, and that seems unlikely during normal operation. Is there a reason to have af that I'm overlooking?

Ron Schroeder

> Honestly, I was thinking of not replacing the af.

> I don't see a compelling reason why this system

> needs it, but I may need education on the matter.

> I have emergency backup heat in the case of

> extended power failure. There are a couple spots

> where the basement piping goes thru the slab

> under doorways and such. Those are about the only

> places I'd be worried about a freeze, and that

> seems unlikely during normal operation. Is there

> a reason to have af that I'm overlooking?

Ron Schroeder

> Honestly, I was thinking of not replacing the af.

> I don't see a compelling reason why this system

> needs it, but I may need education on the matter.

> I have emergency backup heat in the case of

> extended power failure. There are a couple spots

> where the basement piping goes thru the slab

> under doorways and such. Those are about the only

> places I'd be worried about a freeze, and that

> seems unlikely during normal operation. Is there

> a reason to have af that I'm overlooking?

Ron Schroeder

> Honestly, I was thinking of not replacing the af.

> I don't see a compelling reason why this system

> needs it, but I may need education on the matter.

> I have emergency backup heat in the case of

> extended power failure. There are a couple spots

> where the basement piping goes thru the slab

> under doorways and such. Those are about the only

> places I'd be worried about a freeze, and that

> seems unlikely during normal operation. Is there

> a reason to have af that I'm overlooking?

Ron Schroeder

You just named them

But if you can ask the prior owner if they had a problem it wouldn't hurt. There are times if you go into set back you might have a spot or two that can be a problem

EJW

Adam

The dead give away for antifeeze is the green all over the ball valve. The high vent on the scoop shows this also. If you keep anti in the system it will need to be refreshed with new stuff. It is probably pretty corrosive now. If you don't think you need it get rid of it. EJW