leak?

Timco

My hot water boiler keeps dropping pressure...but no leak to be found???!!! Pressure seems to drop from 15 to 5 lbs every other week or so. Could the culpret be the expansion tank going out? Also, one zone ALWAYS has air in it. Ideas? Boiler is a Teledyne / Larrs copper (fin?) type.

Tim

clammy

undergroung loops

What type of home is this you may have heat loops which are under your slab making you loose boiler pressure as the pressure drops your water feeder (pressure reducing valve) feeds water .Thw fresh water has a higher oxygen content and thus as it heats up the air dissolves and goes to the highest loop or one higher then your lowest loop and becomes air bound or another promblem may exist like a small hole in your boiler and may cause the same promblem .While your boiler is running check your chimmey for signs of moisture coming from your chimmey like steam check your flue pipe for signs of corrosion also.Good luck keep us posted to your finding and if all else fails use the find a pro heading and find one not all mechinics are the same peace clammy

Timco

No slab pipes here....all rads. House is 95 years old. Re-piped the manifolds and a run to the back of the house, but no leaks.

Will check for steam...good idea.

T

Timco

No steam from the chimney. The pressure loss only occures when the zone with the air in it is running solo. Filled it up while that zone was running and when the others came on, it shot up to 30# from 20# hot / 15# cold.

T

clammy

re bleed

If your system is all ci rads make sure all rads are bleed check your expansion tank pressure if a diapham type .Also go buy a good gauge maybe one that attaches to a boiler drain and check your pressure there the gauge on the boiler could be off if you satill can't figure it out try the find a pro heading peace it's hard to service something with out seeing it clammy

Timco

Appreciate the hand...I'll re-bleed all and see. I bleed zone 3 every day. If I skip a day, there's a lot of air in the 2 rads on that zone. No pros for a 100 mile radius here in SLC. Will also ensure the exp tank (diaphram type) pressure matches the system. I put a new gauge on it when I rebuilt the manifolds and installed the swing check valves. Do expansion tanks go bad? Slowly leak air and take water? Not the scale of problem to call in the guard...I have plumbed for years and am a journeyman sparkey. Put a great Taco 4 zone controller on it...but am learning the finer points of this hot water boiler thing without becomming a hydronics pro.

Thanks again for the pointers.

Tim

STEVE N

A question...

This zone that gets air... is it on the 2nd or highest floor? If so at 5 psi you are sub-atmospheric on the 2nd floor. You need psi to over come the static weight of water. For every foot of rise from the boiler you need roughly 1/2lb to over come static weight of water. You always figure height x 1/2 lb + 2lb. If it is subatmospheric you will suck air on the second floor from key vents or auto vents. Do you have a bladder tank? Sometimes finding these small leaks is rough. It dosen't take alot of water to lose pressure. I take it you must be closing the fill valve shut off? If the shut off is open then your fill valve must not be working. It could be many things, I am just throwing a few possibilities out there.

Steve

Johnny B

Expansion Tank

Do you have an Extrol type expansion tank? If so, I always do a "Key" test. I simply bank my key on the higher end and lower end of the tank. This should produce a "Hollow" type sound. If the sound is dense, the tank may have expired. Although, I must admit that if the tank or the diaprahm in the tank is bad, the boiler should leak or dump water from the pressure relief valve.

On one occasion, I found that the Water "Autofeed" valve was defective and the boiler would not recover fast enough from the bleeding.

Hope this is of some help.

By the way. If you know how, you can simply spin off the tank and see if it is full. But, please don not do this without instructions.

Timco

House is single floor only....Tank sounds different on each side, Watts diaphram type. Need to find my tire gauge. I did not install an isolation valve on the tank, so I would have to drain the system, however, when I replaced the outlet side of the manifold and removed the tank before, it was really full. Should have checked it then. System was a gravity system, with the old exp tank in the attic, abandoned. Pipes for zones 1 & 2 are 11/2 and 2" even though runs are 70' aprox. Press held last night, but air in both rads (one in basement below runs but even with boiler, and one wall mount...farthest and highest.) I have also never heard the taco air vent 150#, 240psi ever expell air, with the cap screwed half off.

Touchy things...eh?

T

JP_6

Purge Valves

I know you are bleeding from the radiators, but, I was wondering, do you have a purge setup on your returns? Sounds to me like 1. You need a new expansion tank and 2. You have air pockets and need a really good purge, like the one you can get with a purge valve. If the old tank was in the ceiling, I wonder if the old system had a high purge valve in the attic, which may need to be purged. (By the way...Purge, bleed, same thing) and if you do change the tank, for petes sake, put an isolation valve on it this time.

Timco

OK...I found a pipe going up towards the attic comming from the return side of zone 2. As I mentioned, the old exp tank is up there. Do I cap this old horse off or bleed it out, or what? I will get the ladder out and examine it, but assume the valve in the attic neds to be shut for the sys to hold pressure? Should mentioned the system is all forced HW now, but was gravity. Converted 1o-15 yrs ago by a plumber friend of the owner. This may be the lost ark of my problems!

Tim

jerry scharf_3

now that's progress

Tim,

I would not leave a vent on that stub. You could either fill it with water and put a hard cap on it or put a ball valve on the end, then a nipple and cap. The later makes is easy to fill it with water... I would not leave the valve without a hard cap, one bump = a messy day.

jerry