Tankless coil mounting plate leak

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Old 10-08-14, 05:16 PM
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Tankless coil mounting plate leak

Hi,
Well I got another problem with my crappy vailiant boiler. The tankless coil mounting plate and insulation is wet on the right side. The bolt heads on that side are rusted away. The pipes seen on it are cut just above as I have a hot water heater the last few years. Is there even a chance the holes can be tapped if I get a new plate? I know three of them will because of the deteriorated bolt heads.
Posting photo of it.

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  #2  
Old 10-08-14, 05:50 PM
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The copper sweated joint on the right is leaking. It needs to be cut out and replaced.
 
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Old 10-08-14, 05:57 PM
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Mike, you could no possibly have just noticed that, did you? I mean, that didn't just happen overnight!

Gil, the coil is abandoned...

The pipes seen on it are cut just above as I have a hot water heater the last few years
If it's leaking from that area, it's from around the outside of the pipe where it enters the plate.
 
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Old 10-08-14, 07:00 PM
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Haha, you are correct Trooper. I didn't just noticed it. Just figured the rust sealed it from leaking
Had to drain the system to replace a broken pipe in the basement and it got real wet after I had to pull up the lever on that auto fill valve. It was only showing 9-11lbs
I got air out of the attic radiators but no water. After 15 minutes I boosted it to 20lbs and got water and thats when I noticed it really getting wet.
 
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Old 10-09-14, 04:34 PM
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I got air out of the attic radiators but no water
How 'tall' is the house again Mike?

Minimum pressure on the system needs to be 0.432 PSI per foot of elevation from the boiler to the tippy top, PLUS 4 PSI.

Three story homes require more than 12 PSI minimum.
 
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Old 10-09-14, 05:59 PM
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It's a three story city home with 11 radiators. I'm not sure how tall but will measure tomorrow. The Watts valve says "Set 11-15"
Every week or two I have to bleed the air out of the attic ones during the winter. If I don't the pipes on the 2nd floor leading to the attic ones make a sound like water is draining down from them inside.
 
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Old 10-09-14, 06:23 PM
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The Watts valve says "Set 11-15"
Yeah, for up to a two story building. Needs to be higher than that for 3 story...

The reason you need to bleed air is because there's not enough pressure in the system.

Ten foot ceilings, yes? I bet yer gonna need at LEAST 18 PSI MINIMUM, maybe even 20!
 
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Old 10-09-14, 06:35 PM
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You nailed it. I have the 10 foot ceilings. This use to be my in-laws house. They owned it for like 40 years. I remember starting from about 20 years ago they always had this problem. Funny thing is when he called for service they always replaced the valve with the same pressure. After a while he stopped calling them and just started lifting up the lever and filling it up.
 
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Old 10-09-14, 06:48 PM
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Yeah, it's sad that the techs nowadays for the most part haven't got a clue, or just simply don't care.

So if the boiler is in the basement, with 10' ceilings, it's probably a safe bet that it's about 35' from the boiler to the highest piping. (35 X 0.432) + 4 = 19 PSI ... MINIMUM when COLD.

Your boiler is going to have a 30 PSI relief valve on it most likely so that means that you don't want the HOT pressure to be any higher than 27 PSI MAXIMUM (10% less than the relief valve rating).

Your expansion tank has to be big enough to keep the pressure in check.

SOME boilers can go to 50 PSI so in theory you could install a higher pressure relief valve if your boiler is rated for it. It's probably better to have the right size expansion tank though.


So, getting back to that leaking plate...
 
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Old 10-09-14, 07:01 PM
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The expansion tank if 5ft long by 1ft tall. The plate don't seem wet while the heater is up to temp. I'm not sure if its just drying before I see it now because of the heat or what.


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Old 10-09-14, 07:14 PM
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I'm not sure if its just drying before I see it now because of the heat or what.
Most likely. Also, when it's HOT the metals have expanded and the leak is smaller. Leaks on heating systems are hard to find because the drips never hit the floor. They evaporate before they have a chance.

The 'deposits' you see are the minerals in the water depositing as the water is evaporating.
 
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Old 10-09-14, 07:17 PM
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The expansion tank if 5ft long by 1ft tall.
It's probably big enough but you need to make sure that the tank doesn't get waterlogged.

You might have to drain it annually if the system isn't designed in such a way that the air in the system can get back to the tank where it belongs.
 
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Old 10-09-14, 07:27 PM
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It did get waterlogged last year. Kept blowing water out of the relief valve for a few days. After draining it the pressure went down and the water stopped coming out. Thanks for the reminder, I'm gonna check it again.
 
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