Added more water to system after ~8 months.....

Serge

Hi All:

Our contractor installed our system last year (prestige 110 with 60 gal indirect) and hooked them up to multiple cast iron radiators in the house, new ones in the basement.

From reading on this site, I turned the supply to the fill valve off about 8 months ago so that if there were a leak I would know etc. 

Things have been humming along fine since then until this morning when there was no heat.  Checked the boiler and the water pressure was at 5 or 6 lbs.  Opened up the fill valve supply, it filled up to 12 lbs and the boiler started right up.

My question is - do you think I have a leak somewhere?  Or am I worrying about nothing?

I turned the supply off again right after, so I guess I can wait and see too.....

KeithC

water

Check your compression tank.



Is all your pipe visible? If it is, do a thorough check for leaks. If not, a little creative investigation may be in order.

Serge

No, unfortunately...

Most of the pipes are hidden in the walls.....Sigh.

Brad White

Frustrating...

But yes, you may have a leak or leaks somewhere. Given that the pressure dropped six to seven pounds over eight months (sounds like a diet for the slow food movement!), I would suspect slight weeping at valve stems/gland seals.



The weeping would be slow enough that any tell-tale wetting evaporates. The reason I suspect this is that when you use glycol (not that you are, but when you do), that seems to be the weak link, the first place I see weeping with a reminder.



A walk-around with the proper tools, hoping that accessible features are the cause, might be worth doing regardless. Maybe look for any green copper staining?



Now, as another thought, the initial 12 psig was a cold-fill pressure and not at operating temperature, is that correct? Depending on your expansion tank volume, thermal contraction on a temperature drop could be a major portion of that pressure drop. In other words, all of your pressure notations should be at about the same temperature.

Serge

Hey, that's a great idea.....

We just had one of our first cold nights in a long time.  Could some of the pressure loss be from thermal contraction?

But, hopeful thoughts aside, I will walk around and check for leaks.

Thanks!

Brad White

A way to check that

if thermal contraction was the cause of pressure loss, then thermal expansion when it heats, would at least reduce it. What is the pressure when the system is hot?



Now, if you had that low pressure when the system was hot, then my friend, you are back on the leak hunting path.



Another place to look for leaks is at the boiler connections. If the boiler connections are MPT and the first fittings are copper FPT, they tend to weep more than others. The tip I learned is to heat the FPT fitting before tightening and let that extra thermal contraction form a better seal when it cools. No substitute for good wicking and dope though!

Mark Eatherton

Not neccessarily a leak.....

If the tanks air side is pressurized to 12 PSI, and the system was filled to 12 PSI, there was ZERO reserve fluid in the tank. THe diaphragm wasn't extended.



As you heat water, oxygen comes out of suspension. This oxygen constitutes a certain volume. Once that volume is taken out by the air eliminators, it has to be replaced/replenished, or the pressure will drop, as it did in your case.



Try bumping the cold fill pressure up to 20 PSI, and it will have enough reserve due to the expansion tanks diaphragm being extended, to compensate for air elimination.



If it continues to drop, then its time to start sleuthing. Relief valves are notorious for losing water when you aren't looking. Cut the bottom off of a plastic bottle and place it below the relief valves terminus. If there is a leak, there will be fluid in the cup. I call it a "Witness Cup" :-)



ME

Brad White

A great point, Mark

If from a cold fill as you say, there could be 2% air by volume and at 12 psig, larger bubbles than at 20...good call. In a small volume system that could be the difference.



I suppose after the first firing to critical temperature and that air is freed up, I would hope this would not happen. But a first cold start, makes sense!



I did not ask the height of the system and 12 psi is a minimum in my book for even a ranch.  20 psig ought not hurt if there is enough expansion tank volume.  And then your witness cup comes into play.



Speaking of which, I learned a trick some years ago for intermittent leaks. Paper in the cup or area of leak suspicion with a few lines from a water-soluble marker. This way, if you do not return for several days, the evidence is there even if the paper is dry.



Cell phone companies have dots of similar ink inside so they can void a warranty based on immersion.

Serge

Like the explanation....But I found it....

It's the @!@#%! 1" copper union right under the DHW recirc.  I'm tempted to just tighten it myself.  Not sure I should call the contractor for this......But if something else happens will I be at fault?  I'm pretty good with plumbing, but don't want to mess with the boiler stuff too much.

Jean-David Beyer

Another way to lose pressure...

On my system, the near boiler piping is primary-secondary. The air eliminator is in the secondary circuit, right after the closely spaced Ts. The makeup water comes into the bottom of the air eliminator. The expansion tank is in the makeup water line (after the anti-backflow valve and the pressure reduction valve).



The pressure gauge is in the boiler, in the primary circuit, at the output of the heat exchanger. The Indirect hot water heater is plumbed across the primary circuit. If the indirect water heater calls for heat, it appears that I lose about 5 psi of pressure on the pressure gauge. This is no doubt due to pressure drop in the heat exchanger or the piping to the pressure gauge. As soon as the indirect is satisfied, the pressure returns to its normal value.  Were the system to take on water during that interval, the relief valve would have to dump the excess sooner or later, and it does not do that.

Brad White

So...

what was the evidence? Verdigris staining, or visible water? Curious.

Tightening a union is always a two-wrench job. If in doubt, call a pro.

Serge

No green copper stuff....

I was running my finger over  connections and suddenly it had a small drop of water on it.  Waited for about 10 minutes (enough time to get another beer) and ran my finger over the same areas and the same one had a small bit of water there.  That must be it since it's so slow.

Tightened it and haven't seen more yet (about 2 hours later).

Serge

No green copper stuff....

I was running my finger over  connections and suddenly it had a small drop of water on it.  Waited for about 10 minutes (enough time to get another beer) and ran my finger over the same areas and the same one had a small bit of water there.  That must be it since it's so slow.

Tightened it and haven't seen more yet (about 2 hours later).

Brad White

So this...

is keeping you up and not watching Test Patterns on TV? 



Fingers crossed, here is to hoping you found it. Stay vigilant.

BTW, that is one of those things we put in our specifications, regarding going back after several days or weeks to re-check certain mechanical joints which can loosen or "season" with several heating and cooling cycles. This may just illustrate that. It is one of those provisions that is hard to police because it often comes well after project substantial completion or acceptance, often too in the next season.

Bob Bona_4

Oh, Brad

Yet another nugget of information re cell phones.

Good to see you back!

Mark Eatherton

Which is why I HATE unions...

No, don't go there. I didn't say THE unions. I said UNIONS, meaning the mechanical type. :-)



They were lobbied for by the Apartment Associations across America so it would allow their lawn mower pushing mechanics the ability to change out water heaters, boilers etc without having to obtain a permit, under the guise of "maintenance", which in most cases doesn't require a permit.



They see them as "Velcro".



I am of the strong opinion, that if you don't have the skill set/tools/knowledge/ability to cut and thread or solder or silver solder piping, maybe you shouldn't be messing around with the device in the first place...



That, compounded by the fact that 90% of them leak, causes me to NOT use them, and have only lost the argument with the AHJ one time.



Seen way too many hazardous installations/replacements by Joe Homeowner, Week End Warrior at large, stacking water heaters on bricks to make up the difference in height.



Good catch.



ME