boiler pressure not steady on new install

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Old 03-19-10, 01:19 PM
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boiler pressure not steady on new install

Three months ago my oil boiler was replaced with a buderus 142/24 natural gas boiler. The pressure as I understand it from buderus should be 16 psi. That was not he case when the unit was fired up. The pressure would slowly drop to 7-10 psi and then climb slowly back up to 24 psi when the boiler was heating.

So, all the air bleeds were replaced with manuals and three automatic air bleeds. Didn't work.
So, the back flow and water fill valve were replaced. Didn't work.
So the ET30 expansion tank was replaced with the next larger size this past Tuesday. Hasn't worked.
The pressure reading on the gauge and the internal reading on the buderus control panel are basically reading the same.

Recently during the day the boiler doesn't fire as the solar gain is sufficient for the stat not to call for heat. The pressure will go down to 7-10 psi. then as the temperature outside cools and the boiler comes on the pressure will go up to 24 psi.

The system has never blown the pressure relief valve (yet). It also has an outdoor reset. With those kind of pressure readings one would think that water would be squirting out of a pipe,valve, pin hole or whatever. I have not seen any water. Please help. Any ideas or things that I could or should be looking at?
 
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Old 03-19-10, 02:40 PM
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First, 24 PSI is not really high enough to cause anything to 'blow'... the relief valve on the boiler is set to 30 PSI... and you wanna stay about 10% below that.

Replacing the air bleeds would not have any affect on your pressure problem, uneccessary expense.

When you say the internal reading on the Buderus control... what exactly do you mean?

Never trust a pressure gauge... ever... even if it's brand new... they are evil.
Verify the gauge reading with a KNOWN GOOD gauge.

The low side pressure is generally stated as 12 PSI minimum. You would only need 16 PSI if your home were say a three story job... 12 PSI is adequate pressure for up to about 20' or so.

It sounds to me as though you've got Bozo working on your system.

If they replaced the pressure reducing valve (auto feed, auto fill, whatever), and it is properly adjusted, and the manual shut off valve is open, then there's no reason for the pressure to drop below 12-15 PSI when cold.

If they replaced the expansion tank, and it's air charge was properly set to 12-15 PSI before installation, then there's no reason for the high side pressure to go that high.

I think you need to try a different Clown... maybe ClaraBelle is available?
 
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Old 03-19-10, 04:24 PM
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bolier pressure

Yes i realize that it won't blow below 30 psi, but Tuesday morning (new ET installed)it was 20 psi and each morning it goes higher, perhaps 25 tomorrow?

The internal reading is the computer control module that gives the error codes, pressure and temperature etc. It displays a digital read of what is happening. the boiler is a a buderus , high efficiency modulating unit, wish I had the old boiler at this point.

Yes the gauge is new, but I am assuming with the buderus pressure reading being the same as the gauge then the psi reading is correct. One digital one mechanical both read the same, got to be correct.

The 16 psi number came from buderus. Don't know why they claim it to be so high. I got that myself from their website and again from the "hvac contractor". I was told that it was the design pressure for this hang on the wall unit. Right now the boiler serves the basement and the first floor. was hoping to complete the second floor in the future.

I agree that the "bozos" working on my system sure don't seem to care or know much, although it is a long term reputable firm, I have my doubts.

They manually adjusted the PR valve to 15-16 psi. (as I was told, I was there watching him) Yet when the system is cold (manual shut off valve ) it still drops. The air charge in the expansion tank was supposed to be set at 15 psi.

It's a lot of BS and is probably something simple but I don't get it.
 
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Old 03-19-10, 04:51 PM
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Is the boiler piped per the installation manual? Does it have the Buderus primary/secondary module?

Have they tried purging the system? How is it set up (valves, etc.) for purging?

What kind of heat emitters do you have in the house? If radiators, how many/how big? How big are the pipes in the basement? (trying to get a handle on what kind of water volume you have here.)
 
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Old 03-20-10, 08:03 AM
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To expand on what xiphias was asking water expansion is determined by water volume, water temperature change and air volume. The larger the water volume and the greater the temperature change the larger the pressure difference. If you have large pipes and large cast iron radiators you will require a larger tank or see more expansion on a smaller tank. Tanks are sizes on water volume and maximum temperature to keep it simple.
 
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Old 03-20-10, 09:32 AM
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So the ET30 expansion tank was replaced with the next larger size this past Tuesday. Hasn't worked.
Note that the 30 was replaced with a 60...
 
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Old 03-20-10, 10:30 AM
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Shut the boiler and pump off its pressure subsides back to normal pressure its due to expansion isssues If not then your Prv or manual valve is letttng water in . What side of the Pump is the Prv ( make up valve located) ?
 
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Old 03-20-10, 11:00 AM
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The installation looks like it is correctly piped according to the manuals etc. that they left. Their main hvac guy came and inspected and said everthing was good.
I don't know what you mean by primary/secondary modules, please expand.
They didn't purge anything since the installation. There are two valves that could be used for purging. One on the buderus unit and the other on a return line low to the basement floor.
The heat emitters are baseboard
The pipes are copper 1 1/2' from the buderus to 1 1/4' then out to 3/4" & 1/2" through the loops. This is a single zone system and there is a buderus 120 indirect fired hot water heater tied to the boiler.
Also to be noted, no additional pipes were added to this system (except for indirect DHW heater) when the other boiler was removed. In fact I would say there was more water volume in the Kerr Comet 3 oil boiler that was swapped out for this wall hung unit.
 
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Old 03-20-10, 11:25 AM
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That is the problem, when the bolier is operating the psi is high 23-24 psi. When it isn't operating and the water is cool the psi is 7-10 psi. That being said then the prv and manual valves wouldn't be leaking because the pressure has dropped.
 
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Old 03-20-10, 01:42 PM
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Pressure

Are you sure that there is no obstruction between your system and the expansion tank, with a new # 60 tank, which is large enough for a small appartment building, the pressure needle should'nt move at all from even a cold start. Are you sure the
precharge is correct on that new tank. 12 to 15 psi?
Sid
 
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Old 03-20-10, 02:03 PM
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We need to see/know how this system is piped. Is the exp tank on the system (radiation) side or the boiler side?
 
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Old 03-21-10, 05:18 AM
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Originally Posted by xiphias View Post
We need to see/know how this system is piped. Is the exp tank on the system (radiation) side or the boiler side?
The expansion tank should be in reference to the suction side of the pump only, commonly reference the point of no pressure change. the closer you pipe it to the suction side of the pump the more accurate your install. This connection line is the ideal location for Teeing in your PRV.
Where is your tank and prv tied into the system?
 
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Old 03-21-10, 05:58 AM
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For pressure to change that much it is an expansion issue where the water cannot get to the tank or a lack of air in the tank. It can't be anything else as the pressure does not stay up, it only goes up when heated and down when cooled.
It is not a pump or PRV location issue. I don't think it is an issue of location and valves that do not allow the water to expand into the tank because the pressure goes up when the unit is running unless he means it is only going up on a call for hot water and not when he gets a heat call but he says "when heating". We know the tank is big enough.
As everyone else is stating need pic's.
 
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Old 03-21-10, 08:26 AM
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rbeck stated the bottom line really... never mind about the PONPC, or all that other 'perfect way to pipe a system' mumbo-jumbo... all the rhetoric clouds the real issue.

I said it (and others have also) before, and will again (as usual!)...

IF the pressure reducing valve is set correctly, AND it is working properly (not plugged with sediment), AND the manual shutoff valve is open, THEN the pressure will not fall below the setting of the reducing valve when the boiler cools.

IF the expansion tank has the correct air charge, AND the expanding water can 'get to it', THEN there is no reason for the pressure to go too high.

Do not ASSume anything. VERIFY that Bozo and ClaraBelle actually DID set everything up properly. CHECK the pre-charge on the tank FIRST, then CHECK the reducing valve setting.

Remember that you can not check or adjust the exp tank air charge if there is any pressure on the boiler side of the tank. You MUST drop the boiler pressure to zero before checking. If you intend to go with the 16 PSI that the manf is recommending, the air precharge in the tank should MATCH that. So, you should go for 16 PSI in the tank also.

When the boiler is cool, and the pressure is 7-10 PSI, and you loosen the locknut on the pressure reducing valve, and turn the screw clockwise on that valve, can you see the pressure increase? You should... it may happen slowly, so don't go more than one turn at a time, and WAIT a few minutes for the pressure to stabilize before deciding to adjust more. KEEP TRACK of how many turns you go so that you can return to the original setting if you need to.

By the way, those valves are factory set for 12 PSI. Does it appear as if Emmet Kelly turned the adjustment? Look for wrench rash on the nut... and again, you will need to increase that adjustment for your desired 16 PSI.

I'm thinking that they didn't know what they were doing at all... and the expansion tank was depressurized for some reason... and when the low side pressure was at the correct nominal setting... they saw the pressure going too high... and instead of charging the tank properly, they dropped the adjustement on the reducing valve to compensate. Yeah, I know, they are the pros, and know what they are doing, but how many times have I heard that?
 
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Old 03-21-10, 09:59 AM
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rbeck stated the bottom line really... never mind about the PONPC, or all that other 'perfect way to pipe a system' mumbo-jumbo... all the rhetoric clouds the real issue.

Sorry to have clouded the issue
 
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Old 03-21-10, 11:03 AM
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I will check these items this week when the outside temps go up and the bolier goes off. NJ Trooper may have it because it can only be those items, prv and tank. I am assuming these "pros" have set the tank correctly, but I will check this week. The tank has a tee with a pressure gauge and purge valve; above the tee is a ball valve so I could shut the boiler water from entering, drain the water off and take a pressure reading of the tank's air charge.

The manual shut off valve is open, in fact there are two valves. One on each side of the combo prv and back flow prev't. these are always open. but I remember when they were installing the boiler that they had drained the system 3 times due to poor workmanship.(forgot to solder a joint) and another joint leaked as it was only half soldered. Anyway, I am on a well system and that sub'mble pump can kick up alot of sediment.(300 ft deep). If the new prv is clogged with sediment, does this meani it can be cleaned out or do we get a new one?

As far as pics go, I had 19 this morning but something is wrong with my PC or photobucket because it just keeps looping. Any other sites out there? I will send some if needed.

Let me see what I can come up with this week and will post my results. This morning it was 24 psi. later on heat wasn't required and dropped to 7 psi. I was standing there taking pics and the boiler went on and I watched the gauge rise up to 24 psi. So there is real a pattern here. I will report back
 
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Old 03-21-10, 11:04 AM
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No problem really... no apology needed...

And chances are that once OP puts some pics up, I'm betting we will end up back where we started... cuz if the installers can't figure this one out, then chances are very good we'll see lots of things to cloud the issue!
 
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Old 03-21-10, 04:48 PM
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Try flickr.com for pictures.

You can close those valves on the cold water supply to isolate those items as the culprit.
 
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Old 03-21-10, 07:16 PM
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I don't think closing the feed valve will tell us anything... because when the boiler cools, the pressure goes right back to 7 PSI... so we know the valve isn't leaking... if it were, the low pressure would constantly be creeping up and up ... and the relief valve would eventually open...

Instead, what it appears, is that the valve is either set too low, or plugged up... and some of the valves have a strainer that can be cleaned. What make/model is the reducing valve? Is there a 'nut' on the bottom?

What do you mean by photobucket is 'looping' ? I don't particularly care for flicker's interface, but it will work if you can get them up there.
 
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Old 03-21-10, 07:22 PM
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That is another problem of not adding water below 12 psi but right now it is probably a good thing or there may also be a relief valve blow-off every time the boiler runs.
I would agree with Trooper that the screen is blocked or the valve is bad but the pressure problem is an expansion/air charge problem.
 
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Old 03-22-10, 02:40 PM
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Sounds dumb..
Check that the fill pressure reg is installed to flow in the correct direction.
I have put one in backwards (end of a long day) and it took a minute or few of cursing to find that one.
I laugh about it NOW...
 
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Old 03-22-10, 04:27 PM
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Okay the prv is a Watts 1156 FSet 12 -15
set 12-15
range 10-25
This valve does not have a nut on the bottom. Has to come off and pulled apart. Probably better off buying a new one than wasting time on this one if in fact it is faulty. the arrow stamped on it is pointed in the direction of flow so at least it is installed properly. It was a new unit but that doesn't mean it isn't crap. The air charge is to be checked as well I have to get on to the prv screen problem.

By looping I mean that since I am on dial up, loading pics takes forever and when its busy it just keeps going back and forth never loading. Have a 3G stick, works like crap as well the cell phones don't work much at my place either. I am in the middle of a forest and signal strength isn' so great. If there was another way to get pics out that would be great/
 
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Old 03-23-10, 02:11 PM
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boiler pics













 

Last edited by NJT; 03-23-10 at 02:58 PM.
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Old 03-23-10, 03:22 PM
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I was gonna suggest that you email me the pics and I'd upload them, but I guess it's six of one half dozen the other... but you got 'em anyway... Gawd, dial up... you ARE out in the woods! I guess yer lucky to even have that, eh?

One thing that I don't see in the pics is an 'air separator', and air vent... I know you said they replaced some, so you must have them... I guess they are on the radiation? But still, there should be something like a Spirovent somewhere near the boiler...

Did the installers set up the expansion tank with the valve and drain like that all on their own? If so, then they've at least come up a notch in my book... and I think you already said that you know how to use the valves to check/charge the tank, yes? So, go ahead and do that... if you have to add air to the tank, make sure to leave the blue handle drain valve OPEN when you are adding air.

Then go after the reducing valve as mentioned previously...
 
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Old 03-23-10, 04:59 PM
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which way is that old beat up grundfos (system pump) ?
is it pumping into the hydraulic seperator or away from it ?
 
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