68C heat with thermostat off ?????


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Old 12-04-07, 09:10 AM
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68C heat with thermostat off ?????

I have a 20-ish year old, three-zone forced hot water, oil-fired boiler with an insert for hot water. Each zone has a circulator pump at the boiler. Each zone has a control box, one zone's controller is in the same box as the hot water temp control.

If i turn all of the therostats very low (50-ish degrees), I still get heat in at least one of the zones. In fact, one zone gets to about 68F with the thermstat set well below that temp.

I believe the controller for the hot water is turning on the boiler when the temp drops too low (settings are 190/170/10, max/min/delta). However, I do not believe that the circulator pump for any of the zones should be enabled unless the thermostat is calling for heat.

I disconnected the therostat wires from the controller box that has the heat controller (I believe this is the t-stat for the problem zone) and the circulator pump still came on.


Prior to this season I had no problem. Since last season my wife had a heating contractor in to clean/tune the boiler and install a mixing valve on the hot water line.

Did the heating guy change my controls? Am I missing something obvious? Is my diagnosis flawed?
 
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Old 12-04-07, 03:37 PM
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There should be some 'flow-chek' valves on your system. I think what you are experiencing is 'gravity flow' where the heated water is flowing to the zone, while the cooled water is flow back causing circulation in the zone.

Is the zone that's heating up the highest one in the system ?

Flow-chek valves are designed and used to prevent this. It's very possible that valve was turned the wrong way when he was working on the system.

Can you post some pics on www.photobucket.com (free) and put a link here to those pics ? We'd be able to spot the flow chek in a hurry if you did.
 
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Old 12-04-07, 04:01 PM
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Circulator Came On?

Do you know for a fact the circulator came on or are just presuming so because the pipes got hot? If the presumption is true, it's a common mistake. As Trooper said, if a flow check is stuck open, the temperature difference in the boiler & the water in the zone will cause heated water to migrate toward the colder zone.
 
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Old 12-04-07, 06:43 PM
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more info and pics to help

Thanks for the attention, guys. I *thought* that the circulator had come on, but, to be honest, it's hard to hear or feel with the boiler running.

The pipe for the "problem" zone was definitely hot while the other two were cool. The "problem" zone is the same height (second story) as another in the system and further from the boiler.

Is there a more controlled test I can run?

I have posted some photos on photobucket (d-cubed/boiler).

Link to album
 

Last edited by NJT; 12-04-07 at 07:15 PM. Reason: added link to album
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Old 12-04-07, 06:58 PM
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Hear or feel

To stop the burner, just unplug it. There is a plug in the wiring going to the burner.

It took some digging to find your pics. Here is a link directly to the boiler album.

http://s270.photobucket.com/albums/j...-cubed/boiler/
 
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Old 12-04-07, 07:05 PM
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First thing I'd do is take the handle off that ball valve on the unused zone and hang it on a nail on the wall. 190* water in the face can be VERY uncomfortable !

I _think_ those gadgets next to the ball valves are your flow-check valves... and the screws in the top should be all the way in... but I'm not certain... never fooled with that type.

Can you get a closer up of one of them ?

By the way, it appears that the unused one may be leaking... probably not now, it may have sealed itself, but just so ya know.
 
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Old 12-04-07, 07:27 PM
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Uncomfortable?

Originally Posted by NJ Trooper
First thing I'd do is take the handle off that ball valve on the unused zone and hang it on a nail on the wall. 190* water in the face can be VERY uncomfortable !
Trooper is the master of understatement tonight. I suggest either a soldered on cap or a soldered on male or female adaptor with screw on cap or plug. I KNOW what 190º water feels like. It HURTS. Been there, done that, don't want to again.
 
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Old 12-04-07, 07:36 PM
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more pics

Good eye - the unused valve had certainly leaked. And I did remove the handle as suggested.

I added photos of the valves - two different ones suggesting a replacement of at least one at some point in time.
 
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Old 12-04-07, 08:53 PM
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Yes, those are ineed your flow-chek valves, but I'm still uncertain as to whether that thumbscrew needs to be turned clockwise or counter-clockwise. I believe the proper setting of those valves would be with the thumbscrew turned completely clockwise.

One of them could be hanging open. Inside those there is a weighted disc that prevents back flow. When the circulator runs, the pressure lifts the disc. There is no spring inside, so a piece of crud could easily get lodged under the disc and prevent it from closing.

I'm 99% sure that one of those valves is your problem.

The photo showing two valve... the rear most one appears to have some leakage 'growth' around the stem. If you turn it, it may start leaking more... best to leave that one alone.

Can you identify the one that serves the zone that's heating improperly ?

The first one that I thought might be leaking ... if my eyes aren't playing tricks with my brain, it almost appears as if that pipe is even pushed out the end of the valve somewhat. I'd be very careful working around that one. Just a wee wiggle on that pipe might be enough to start leaking badly ...
 
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Old 12-05-07, 09:34 AM
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focus on flow-check valve......

Your hypothesis sounds good. When I get home from work tonight I will try to id the valve for the "problem" zone. After you pointed out the leak (old) on the unused zone, I payed more attention to the other three and noted the leakage that you also called out. Thanks for the warning on disturbing a potentially weak connection.

Without doing any further work or diagnosis, I am thinking that the check valves should be replaced across the board. Do you concur?

From a pure installation standpoint, such a job looks relatively simple. My concern is the logistics of the prep and follow-up to the actual replacement: draining, isolating, refilling and bleeding. Is the job as daunting as I am making it appear?

Should I start a new thread (how do I change check valves? ) for these questions?
 
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Old 12-05-07, 03:46 PM
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Originally Posted by d-cubed
... I am thinking that the check valves should be replaced across the board. Do you concur?

Is the job as daunting as I am making it appear?

Should I start a new thread (how do I change check valves? ) for these questions?
Taco apparently doesn't make that style valve any longer, and I couldn't find any tech info in a web search. That might color your decision... The only ones they sell now are cast iron construction. Bell & Gossett also makes several, and at least one type is the bronze variety. Check their website: www.bellgossett.com ...

I don't think it would be a difficult job, but my perspective may be 'tainted' by experience. How are your soldering skills ? Do you have a torch and a tubing cutter ? These are the things you need to consider.

Fortunately, you have all the right valves in the right places, and you would only need to do very minimal draining. Close the valves on the returns above the pumps, close the valves on the supply next to the check valves, and only drain enough from the boiler to empty that horizontal length of pipe. No more than a couple gallons I would guess.

Before you pressure it back up, check adjust the air charge in your expansion tank too...

You might also want to evaluate whether or not the flanges on the circs are leaking... it might just be rust, or could be minute leakage. You would need to drain more water if you needed to change those gaskets though.

Now... before you go making plans to change the valves, you might try rapping on the check valves with a hammer... I'm NOT suggesting you WAIL on them ! Sometimes a little rap rap is all it takes to dislodge crud. You could also try turning the thubscrews all the way open and all the way closed again. (might wanna stay away from that one that has the 'growth' around the thumbscrew though, hopefully that's not the troublesome one, but it just might be...)

No need to start a new thread I don't think...
 
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Old 12-05-07, 06:17 PM
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identified, opened and rapped the valve.....

Ok, I identified the "problem" zone's chek valve (it's not the leaky one). I opened and closed it a couple of times and rapped it both when open and closed. I am now waiting to see if the zone will get hot, or stay cool, when the boiler fires.

I did go to Taco's site - they do offer the 3/4" bronze (219-4), but they don't show a pic.

http://www.blueridgecompany.com/radiant/hydronic/409

I also found some on eBay.

I do have the skills and tools to cut and solder. Your tips on isolation and draining make the job seem kind of easy. Hopefully, however, I won't even need to do the job.

BTW, I read on Taco's web site that you can take apart and clean the valve.
 
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Old 12-05-07, 06:57 PM
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Yep, I found 'em ... I was looking for pictures, and when I saw the cast iron one, I thought that was the only one they still are selling. Once I looked at the chart though, I saw it.

That particular valve is pretty restrictive actually. If you look at the chart, at the "Resistance in feet of pipe equivalent/CV" you will see that valve is equal to 143 feet of pipe in friction loss... that's a lot.

Excess friction loss in a piping system means that the flow through the system will be less, all other things being equal.

If you don't have a problem with the rooms toward the ends of the heating loops being cooler than the others, then you don't need to consider this: If they _are_ cooler than the others, it _might_ indicate that there might not be enough flow in your system.

I wouldn't mention this unless you were already considering changing the valves... but if you do change them, I'd recommend using a less restrictive one.

The 218 in cast iron... look at the difference in the feet equivalent and the CV ( which is the flow in GPM to cause a 1 PSI drop across the valve). It's equivalvent to only 36' of pipe and you could flow twice as much water before having a 1 PSI drop... If you used these, you would pipe them using 3/4" threaded adapters.

Flow through the 3/4" loops should be around 4 GPM, as a point of info.

Hopefully you won't need to change them though.

I don't think Blue Ridge sells retail. Patriot-Supply does though. www.patriot-supply.com , and their service is great.

I'm willing to be the cast iron is a whole lot cheaper than the bronze as well.

Just some things to think about...
 
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Old 12-05-07, 07:03 PM
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Ya know though... on second thought, since you are zoning with circulators, you probably have MORE than enough flow in each zone anyway, and perhaps that was one of the reasons they put a restrictive check valve in there...

If you had electric zone valves, and one circulator for all zones, you might wish to change, but 'if it ain't broke..."
 
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Old 12-05-07, 07:32 PM
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I think the problem is solved....

It's been a couple of hours since I banged and opened/closed the valve and the "problem" zone is now relatively cool. I think that we have found and fixed the problem, but I will know for sure tomorrow.

If the problem is not resolved, I think I will try to clean the valves, but have a spare around in case a seal has taken a set and I can't get it back together w/o leaking.

If that doesn't work, I will replace the valve(s). Your recommended supplier, Patriot is actually the seller I found on eBay.

I will also cap the spare zone as Grady suggested.

If my zone stays cool, I'll consider mission accomplished for now. If not, I'll post back here tomorrow.

Trooper and Grady, Thanks for all the tips and advice, your input has been great.
 
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Old 12-05-07, 07:39 PM
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d-cubed

Glad to be of service. We do this because we enjoy it. It's always more pleasureable to work with someone who understands & works with us. Good luck in your repairs. Should anything else crop up. We're here & will do our best to help. Just be careful, this site is addictive.
 
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Old 12-05-07, 08:24 PM
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Originally Posted by Grady
Just be careful, this site is addictive.

Really ? gee, I hadn't noticed !
 
 

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