Condensation in my boiler....this normal?

FloMo201

Hi Everyone,

I have a Peerless MI boiler that was installed prior to this winter. We've had some warmer weather now and the heat has been staying off most of the day. We recently noticed that is water dripping from the draft hood in the front of the boiler. Looking in, there is a lot of moisture on the sides but is dry in the middle where the flue opening is.

We watched it the other day and from what we can tell the moisture forms early when the boiler is running from 80 degrees up to 130-140 degrees. After that it seems to start drying up. We also noticed that the circulator pump didn't turn on until the boiler was hot. My old boiler it would turn on immediately.

This boiler has a control panel on the front where the water is dripping. I'm setting up an appointment with my installer to have it checked. What should I expect he do when figuring this out? I want to be armed with educational info.

Would this be a venting issue or a combustion issue? The flue is 6" from the boiler and connects to a larger flue pipe. The old boiler which was also sized the same used a larger vent pipe. It is not a masonry chimney...the exterior is vinyl sided like the house.

Thank you, Flo

hot_rod

Got a pic of the boiler piping?

Here is the page from your manual describing what is required.

Personally I feel the boiler manufacturers recommendations are a bit vague.
A bypass? Adjusted how and when??

FloMo201

@hot_rod , yes here are some pictures

mattmia2

Does the thermostat turn off around the time that the circulator starts? Sounds like the boiler is cold start, the circualtor is running on an aquastat and the heat call is ending on the anticipator/cycles per hour of the thermostat around the time that the boiler gets up to temp. The boiler will condense when it is cold but the system should be designed such that the return water temp is hot enough to keep it from condensing once the system reaches steady state. It might be a longer anticipator setting on the thermostat or a bypass from supply to return or both.

What kind of emitters("radiators") does your system have, it is cast iron radiators or fin tube or convectors or what? Did it always have a modern gas or oil boiler or was it originally a coal gravity system?

FloMo201

@hot_rod , also some pics of the moisture in the boiler

hot_rod

The boiler needs to "dry out" every time it cycles. Short cycles 5 minutes for example may not be long enough. Or the boiler never reaches adequate return, after 10 minute or longer runs. In either case a means of protecting it should be piped in.

The condensation you don't see are a big problem also, the masonry chimney. What type of cap on the chimney? Any signs of condensation up there?

FloMo201

@mattmia2 , No, the thermostat calls for heat well beyond when the boiler hits 180 degrees. I have baseboard throughout the house. The circulators do not start until the boiler water temp is somewhere between 130-140 degrees. And with that, the day we did the observation, after the circulators started the temp reading only fell a couple of degrees. All of this moisture is occuring between 80 - 130ish degrees before the circulator even turns on

FloMo201

always gas. my old boiler was also gas. It was about 30yrs old and I dont remember the brand....Im the second owner and Ive only been in the house for about 2 years. The exterior was blue..while my new one is green.

hot_rod

as @mattmia2 suggested, ALL boilers are condensing boilers from a cold start. The key with non-cons it to get that return up above 130 within a few minutes.

A work around would be to hold the circulator off until a higher boiler temperature, 150- 160 maybe?
But the proper device to give you 100% protection would be best.

FloMo201

Thank you both for the info. I am meeting with my installer on saturday. I will let you all know what he says.

Flo

kcopp

What is the humidity like in your basement?
The circulator delay feature is on newer boilers to stop the boiler from being in condensing mode for long periods of time.

FloMo201

Hmmm...I honestly don't know the humidity level in the basement, but i do have a battery powered temp/humidity sensor that I can put down there.

Yesterday we put the heat back on and took additional notes for my installer. The boiler took about 10 minutes to go from 80 degrees to 180. The pumps (there are 2) turned on at 125 degrees but the draft hood already had moisture build up and was dripping out. The temp did not drop significantly when the pumps turned on. It took about 3-4 minutes to get to 125. Another 2-3 minutes and the boiler was about 150 degrees and the moisture was starting to dry out. By 180 degrees the hood was dry with only trace amounts of moisture right at the draft hood opening.

Perhaps everything is fine and this is just normal. From reading here I know the moisture is not good and can rot things out....so i was concerned there maybe a problem. Will let you all know what the humidity level is later in the day.

Thank you again for your help! Flo

hot_rod

Not great, how long does it take for the return temperature coming back to get above 130°F?
That is when it will stop condensing. That should be 10 minutes or less. It would be good for the boiler to run 15 minutes or more everytime it is fired and warmed up to dry out the flue and masonry chimney also.

Do you have copper tube baseboard or cast iron?

FloMo201

Fintube baseboard througout the house. Chimney is not masonry...its vinyl sided...so b-vent all the way I guess. Yesterday it was 2-3 minutes to go from 125 to 150. I didn't really notice any drop in temp on the display when the pumps turned on. It seemed to hold 125 and just kept moving up from there.

FloMo201

Oh....the return water temp....I really dont know...what i posted was based on the digital display.

So...my installer is coming over saturday morning. What should he be doing to assess and analyze what is going on? I've done a contractor lookup here and the closest one is 75 miles....so if one of you guys were coming to my house....how would you go about diagnosing? Maybe that will give me an idea if my guy is okay, or if I should consider someone else.

Thanks again, Flo

HomerJSmith

Well, you have a chase from the exit out of the basement to the top of the roof. Is the chase on the gable or eaves? Which direction does the prevailing wind come from?

You have a vent damper, but they are not fully sealed. Cold air could be coming down the flue and chilling the b-vent and draft hood. Cold air is more dense and wants to fall. The chase may not be insulated which it should be for an exterior chase and the cold air could be surrounding the b-vent. This is problematic if the b-vent run is long. In other words, cold air is moving down the flue to the boiler. All that cold air in the flue must be heated to provide buoyancy for the flue gases, but before that can happen the moisture in the air and burnt gasses condenses on the draft hood which is colder.

Flue gasses are extremely acidic at about 3.5 PH. You could measure it with PH strip tape. The sooner everything heats up the better it is. What you want to prevent is sustained condensation. It may be your old boiler (probably a Crown or Burnham) was doing the same thing, but you didn't notice.

Installing a bypass, I have used a Taco I-series setpoint mixing valve with a sensor. But, there are other alternatives that Caleffi and others manufacturers make.

You know that concrete block walls below grade can transmit moisture from the outside if a vapour barrier is not used on the exterior raising the room humidity. You would not even notice. A cheap moisture meter like Harbor Freight sell could determine that.

That's my take.

FloMo201

Humidity in the basement is 38%. I guess I am confused what a bypass would do here...not questioning, just want to learn. The pumps stay off until the boiler hits 125 and after the pumps come on the temp in the boiler doesn't drop....it keeps getting hotter. The moisture is occuring when the boiler is on its way up to 125-130 and then by 140-ish it starts to dry out. It only took 5 minutes to get to that point from cold. That doesnt seem like a long time, but maybe it is?

The chase is on the north side of the house and the wind does generally blow north to south. The height is maybe 30-35 feet.

hot_rod

Maybe have your heat off an hour before the installer arrives so you can have a load condition to watch.

They should have a temperature gauge, IR camera or point and shoot temperature gun. Fire it up and just watch the temperature returning.

If the gauge in or on the boiler reads 125, no way you have 130F or more coming back.

You want an accurate "return temperature" protection method.

Usually with a low mass, low water content system like you have, with a properly sized boiler, you should not have a long condition of cold return temperature. It is more common in slab radiant, cast radiators, large pipe conversions.

You may be fine, just confirm the warm up cycle time period.

With a B vent system there is a cap on top, that will also show signs of extended condensation conditions.

Shane_2

Personally, I think you might be fine. If there was a way to increase the pump turn on temperature to 140 or 150 you would be even better.

Very wise of you to notice this and ask about it.

FloMo201

Thank you everyone. This forum is incredibly helpful. I will let you all know what happens on saturday. Tomorrow is supposed to be warm, so Im going to leave the heat off for the night. That will allow him to make his observations from a cold start. I also bought some PH test strips from amazon.

I am wondering....this boiler is using a 6" vent while the old one is larger. The connection was made with a reducer into the existing b-vent. Is it possible that the b-vent going 35-ish feet is just too big and the new boiler isnt warming the thing up fast enough to create a good draft? I dont feel any heat coming back out the draft hood.

Regarding the cap on the chimney....tomorrow I will try and scope it out with a pair of binoculars....good thing I'm bird watcher! LOL.

Have a great day everyone and thank you for your help

Flo

HomerJSmith

All things considered, you're probably ok. All boilers condense from a cold start as said.

A 35' b-vent is a lot of cold air to move out and a lot of metal to bring up to temp. If it really bothers you, try this to shorten the time the boiler goes from 80 degs to 130 degs. Does the control offer an adjustment on when the pump turns on? If so adjust it to a higher temp. I can't imagine a pump moving cold water into a boiler and a not affecting the boiler water temp. But what you describe with a 35' flue is, I think, is unavoidable. That is, the condensation occurs much before the pumps turn on.

The other vent connected to the common vent is from the water heater? Is it standing pilot? That would help mitigate b-vent temps.

You could increase the time that the pumps turn on by using a "delay on make" relay set to a couple of minutes more when the pump turns on. That would allow the boiler to reach a higher temp before the pumps turn on. But, will it stop your condensation as you state?

I have questions about your piping, number of thermostats, the black pump near the window, etc.

With what you describe, do you need a bypass, ah, no. A bypass is needed for a sustained condensation operating condition.

FloMo201

@HomerJSmith .....I will ask on saturday if the control can be adjusted to start the pumps at a higher temp.

Yes the other vent connection is my hot water heater and it is a standing pilot. During this, "homeowner analysis" time, I can say that Ive never seen any condensation at the hot water heater and when that is firing on its own...I can feel cold air rushing through my fingers at the water heater's draft hood.

I have 4 thermostats, that black pump is the secondary pump....i asked the installer about this set up when it went in. He told me it is primary/secondary. the green pump send water in a loop through the boiler while the black one sends water through the house. There is a section of pipe behind the boiler and I can feel the cold water coming back, but before it goes back into the boiler it is somehow mixing and its hotter and gets hot rather quickly.....perhaps that is why I am not seeing a big drop in temp on the front panel when the pumps turn on?

Thank you, Flo

HomerJSmith

Pics from a different angle showing the piping would be helpful. Is the black pump an Grundfos Alpha pump? Your pipe sizing bothers me. The zone valves are on the return, I guess. I'm just curious. If primary and secondary, you would want a "delay on make" relay on the black pump and not on the green pump. That would circulate the water only thru the boiler, not the sys, and raise the boiler temp faster.

FloMo201

@HomerJSmith , some more pics for you. I believe the zone valves are on the return. I am basing this on the arrows on the pumps showing the direction of flow. The flow direction arrows lead me to believe both pumps are moving water away from the boiler. Both pumps are Tacos.

Thank you, Flo

hot_rod

Makes me wonder why it would be piped primary secondary? Which with the new pics it seems to be. P/S piping does not guarantee boiler protection. I would guess that boiler could be direct piped to fin tube, like the manual shows.
Or is there a low temperature zone, or planned one?

FloMo201

@hot_rod , ....all the zones are baseboard. We had no plans on doing anything like radiant. I was between 2 different installers and based on responses I had gotten here, I decided to go with the guy I used. From the responses it sounded like some additional protection for little cost added to the install.

Thank you, Flo

HomerJSmith

I stand on my "delay on make" relay on the Taco blk pump. That would allow the secondary boiler circuit to run without bringing cold sys water back into the boiler raising boiler water temp faster. You can set the minutes that pass before the blk pump turns on. This would only provide boiler protection on start up which seem to be the problem with the condensation. You are going to get condensation on a cold boiler on startup whether you have a bypass or not. It's the length of time that's important. With s P/S setup you have a bypass thru the closely spaced tees if the sys pump isn't running.

Normally, a ECM pump is used when zone valves are used since you have multiple thermostats controlling the zone valves and all the zone valves don't open at the same time.

FloMo201

Good morning all and thank you again for all your help and insight. I will keep you posted after my guys by tomorrow. I will certainly ask about the delay on the black pump.

Stay well all, Flo

EdTheHeaterMan

HomerJSmith said:

I stand on my "delay on make" relay on the Taco blk pump. That would allow the secondary boiler circuit to run without bringing cold sys water back into the boiler raising boiler water temp faster. You can set the minutes that pass before the blk pump turns on. This would only provide boiler protection on start up which seem to be the problem with the condensation. You are going to get condensation on a cold boiler on startup whether you have a bypass or not. It's the length of time that's important. With s P/S setup you have a bypass thru the closely spaced tees if the sys pump isn't running.

Normally, a ECM pump is used when zone valves are used since you have multiple thermostats controlling the zone valves and all the zone valves don't open at the same time.

Not absolutely necessary based on the Taco 007 Pump Curve. As long as the GPM is within the range of say 3 GPM to 10 GPM, the curve there is relatively flat. Less than 2 ft of pump head (technical jargon for less than 1 PSI pressure) so noise and/or motor overheating will not be an issue... Assuming MI-5 boiler. If it is an MI-6 boiler then 12 GPM will just have a little over 2 ft. pump head. That all depends on what the equivalent length is on the longest loop when all zones are open. Since that Black Pump comes with the boiler, There is no need for the TACO 007e in this case. IMHO

Mr.Ed

PS Edit:
Homer, I agree that the ECM pump might be a better choice on some systems that are more complicated piping and zoning design. Just in this case, no need for the more expensive pump.

hot_rod

EdTheHeaterMan said:

HomerJSmith said:

I stand on my "delay on make" relay on the Taco blk pump. That would allow the secondary boiler circuit to run without bringing cold sys water back into the boiler raising boiler water temp faster. You can set the minutes that pass before the blk pump turns on. This would only provide boiler protection on start up which seem to be the problem with the condensation. You are going to get condensation on a cold boiler on startup whether you have a bypass or not. It's the length of time that's important. With s P/S setup you have a bypass thru the closely spaced tees if the sys pump isn't running.

Normally, a ECM pump is used when zone valves are used since you have multiple thermostats controlling the zone valves and all the zone valves don't open at the same time.

Not absolutely necessary based on the Taco 007 Pump Curve. As long as the GPM is within the range of say 3 GPM to 10 GPM, the curve there is relatively flat. Less than 2 ft of pump head (technical jargon for less than 1 PSI pressure) so noise and/or motor overheating will not be an issue... Assuming MI-4 boiler. If it is an MI-5 boiler then 12 GPM will just have a little over 2 ft. pump head. That all depends on what the equivalent length is on the longest loop when all zones are open. Since that Black Pump comes with the boiler, There is no need for the TACO 007e in this case. IMHO

Mr.Ed

PS Edit:
Homer, I agree that the ECM pump might be a better choice on some systems that are more complicated piping and zoning design. Just in this case, no need for the more expensive pump.

I think turning either pump off would stop any heat flow? That is the P/S concept, disconnecting the pumps hydraulically speaking. Or turn both off . But it is still a bang/bang solution.

I'm not convinced P/S is needed? Or a good match for a low mass zoned system? As zones open and close, gpm changes you constantly have temperature blending at the tees. I'd rather see constant SWT based on ODR.

EdTheHeaterMan

hot_rod said:

I think turning either pump off would stop any heat flow? That is the P/S concept, disconnecting the pumps hydraulically speaking. Or turn both off . But it is still a bang/bang solution.

I'm not convinced P/S is needed? Or a good match for a low mass zoned system? As zones open and close, gpm changes you constantly have temperature blending at the tees. I'd rather see constant SWT based on ODR.

Agree but I may have made the same mistake after reading "Pumping Away And other..." and "Primary Secondary" ...just to be betterer than the other "uninformed" competitors. Selling benefits of "more betterer stuff" than the other guy. Until I teached myself more stuff laterer on in my edumacation about them heater thingies. 'cause I can read.

Mr. "Special Ed"

HomerJSmith

I'm sorry, this must be my dense day, but Ed I just don't get what you're saying. Yes, the curve for a 007 is flatter than any other 00 circulators. However, it isn't what I would call a flat curve. I think B&G 100 as a flat curve.

My concern was when the shortest zone was open and the other zones were closed that the velocity in GPM may be higher than 6 GPM, which would be the max for 3/4" copper pipe. I was thinking pipe erosion. Of course, that is inconsequential as what is, is.

I'm wondering what an MI-5 or 6 boiler has to do with the blk pump as the blk pump is in the primary circuit. The green pump is pushing water thru the boiler.

Turning off the green pump (secondary circuit pump) would most certainly interrupt the heat flo and cause the boiler to reach high limit. However, turning off the blk pump (primary circuit) wouldn't interfere with the flo thru the boiler circuit.

I thought the concern was condensation on startup. Flo said, "All of this moisture is occuring (sic) between 80 - 130ish degrees before the circulator even turns on." Not much one can do about that. All the heat energy is going into raising the boiler water temp, no influx of cold water. And...Flo said, " The pumps stay off until the boiler hits 125 and after the pumps come on the temp in the boiler doesn't drop....it keeps getting hotter."

My only concern was getting from a cold start to a non-condensing state as fast as possible. As hot_rod stated getting to 150 deg boiler water before the pumps turn on would be ideal. But, that may not be possible thru programing.

It will be interesting to hear what happens on Saturday.

Of course, an oversized common vent can be problematic.

FloMo201

Hi Everyone......well, bursting everyone's bubble. He called me and had to reschedule due to a family emergency. I am now on for Wednesday.....but looking at the weather, I don't think we'll have an opportunity to keep the heat off long enough to get the boiler that cold. We'll see how this plays out.

Tell me more about an oversized vent. The vent on the old boiler was definitely bigger and the hot water heater always shared the same vent. The new boiler has 6" stamped in the vent pipe. I am looking at the reducer and it could be 8" to 6"...I say that only because the larger vent pipe is about an inch bigger all around than the smaller vent pipe. You can see it best in the first photo posted.

Well...have a great weekend everyone. Flo

hot_rod

HomerJSmith said:

I'm sorry, this must be my dense day, but Ed I just don't get what you're saying. Yes, the curve for a 007 is flatter than any other 00 circulators. However, it isn't what I would call a flat curve. I think B&G 100 as a flat curve.

My concern was when the shortest zone was open and the other zones were closed that the velocity in GPM may be higher than 6 GPM, which would be the max for 3/4" copper pipe. I was thinking pipe erosion. Of course, that is inconsequential as what is, is.

I'm wondering what an MI-5 or 6 boiler has to do with the blk pump as the blk pump is in the primary circuit. The green pump is pushing water thru the boiler.

Turning off the green pump (secondary circuit pump) would most certainly interrupt the heat flo and cause the boiler to reach high limit. However, turning off the blk pump (primary circuit) wouldn't interfere with the flo thru the boiler circuit.

I thought the concern was condensation on startup. Flo said, "All of this moisture is occuring (sic) between 80 - 130ish degrees before the circulator even turns on." Not much one can do about that. All the heat energy is going into raising the boiler water temp, no influx of cold water. And...Flo said, " The pumps stay off until the boiler hits 125 and after the pumps come on the temp in the boiler doesn't drop....it keeps getting hotter."

My only concern was getting from a cold start to a non-condensing state as fast as possible. As hot_rod stated getting to 150 deg boiler water before the pumps turn on would be ideal. But, that may not be possible thru programing.

It will be interesting to hear what happens on Saturday.

Of course, an oversized common vent can be problematic.

Still some confusion or difference of opinion on which loop is the primary loop?

A wise old rep/ author/ trainer/ humorist tells me the loop with the expansion tank connected to it is always the primary. Is that something Gil declared once upon a hydronic revelation ? So as I see it, the green circulator is the primary?

As far as holding that one off, the boiler manufacturer should make the call. As CI boilers shrink in size and water capacity, and maybe thinner castings, possibly they always need some flow to prevent hot spots?

But in a single pump system, that would be the only pump to delay on?

So my thought would be a thermostatic mixer. Always flow thru the boiler, but always proper temperature protection also. No electronics involved.
It's like slipping the clutch in your truck until the load starts to move.

EdTheHeaterMan

@HomerJSmith... My experience is Black Pumps are OEM pumps. Primary loop is the loop with the expansion tank making the system pump the primary pump and the boiler pump the secondary loop pump. But since both pumps are identical in the curve that doesn't really matter. Finally The shortest loop only calling may cause 6 GPM in which case I would throttle a valve on that loop until velocity noise was non existent, then tighten the packing nut and remove the handle adding a tag (with a note) why the valve is partially closed. Still don't need to pay more for a more expensive pump..

We were talking about condensation, however, I copier your comment and addressed that comment. Maybe a little off topic however, the ECM pump is also a little off topic. Bottom line is that i don't believe the OP needs to purchase a different pump and just needs to find out if the return to the boiler is warm enough fast enough and if the on cycle is long enough so the boiler does not fail prematurely. That boiler should last at least 30 Years but may fail within 20 if there is too much condensation.


A can't think of anything worse than Premature Evacuation of a boiler, resulting from a leaking section, caused by condneseption.

Did I say that right?

Mr.Ed

hot_rod

EdTheHeaterMan said:

@HomerJSmith... My experience is Black Pumps are OEM pumps. Primary loop is the loop with the expansion tank making the system pump the primary pump and the boiler pump the secondary loop pump. But since both pumps are identical in the curve that doesn't really matter. Finally The shortest loop only calling may cause 6 GPM in which case I would throttle a valve on that loop until velocity noise was non existent, then tighten the packing nut and remove the handle adding a tag (with a note) why the valve is partially closed. Still don't need to pay more for a more expensive pump..

We were talking about condensation, however, I copier your comment and addressed that comment. Maybe a little off topic however, the ECM pump is also a little off topic. Bottom line is that i don't believe the OP needs to purchase a different pump and just needs to find out if the return to the boiler is warm enough fast enough and if the on cycle is long enough so the boiler does not fail prematurely. That boiler should last at least 30 Years but may fail within 20 if there is too much condensation.


A can't think of anything worse than Premature Evacuation of a boiler, resulting from a leaking section, caused by condneseption.

Did I say that right?

Mr.Ed

As I see it the green pump is pumping away from the expansion tank, if so it is the primary and also the "boiler" pump.

The black one becomes the system (distribution) and secondary pump, aka circulator.

Doesn't matter which is OEM based on color, if they are both 007 they are interchangeable, in location.

A delta P would be a nice upgrade on a zone valved system.

With only one small zone calling, maybe 1 gpm or less, the 007 may be over-pumping. Hard to say without analyzing the system. 4 or more zone valves is a good time to consider a PAB to flatten the curve even more.

An indicator would be whooshing noise in the fin tube when only 1 zone, the smallest is on.

HomerJSmith

I've been fighting that P/S controversy for longer than I can remember. My contention was that the heat source was the P and the load was the S. (That makes sense) I've seen it with the P as the load and the S as the heat source, so that I have given up on this years ago. So we are going where the Xtank is connected as the P? Why does the Xtank make it primary? Does everybody know this. I guess it's convention, without thought? It might have been a sensible idea in the past. I guess we need a dictionary of hydronics.

Let me get this straight before I make another blunder ( I have a limit of three a day), we're going with the Xtank def?

hot_rod

My thought would be the expansion tank establishes the PONPC. So a good place to start defining from:)
I don’t know there is a definitive answer. I’m going with the guy that wrote the books on the subject of P/S, Pumping Away, and other classics of hydronics.

Seems we look back to Gil of B&G and perhaps even back further to his teachers for guidance on matters like this

EdTheHeaterMan

I see your point Bob. I got the pumps backwards. That pump curve explanation is great for understanding the point of the benefit of a flat curve.

TACO 007 v. B&G 100

hot_rod

HomerJSmith said:

I've been fighting that P/S controversy for longer than I can remember. My contention was that the heat source was the P and the load was the S. (That makes sense) I've seen it with the P as the load and the S as the heat source, so that I have given up on this years ago. So we are going where the Xtank is connected as the P? Why does the Xtank make it primary? Does everybody know this. I guess it's convention, without thought? It might have been a sensible idea in the past. I guess we need a dictionary of hydronics. Let me get this straight before I make another blunder ( I have a limit of three a day), we're going with the Xtank def?

The would throw a wrench in the works of the boiler loop being the primary loop😗

DanHolohan

Gil told me the primary loop is the one that contains the compression tank. All other loops are secondary, or in some cases, tertiary. I hope that helps.