Pickup Factor...

Jamie Hall

Hatterasguy said:

Charlie from wmass said:

In order to make sure that we get paid and the customer does not become disgruntled contractors hold fast to the 1.33. Most consumers do not want a degree in Steam engineering to understand the working of their system. This is unfortunate because it ends up costing them fuel but if we stay at 1.33 that is minimized.

You can't fix stupid.

In those instances, of course you give them the 1.33 and go home.

The discussion is really about how close you can get down to the heatloss of the building if you are diligent, tenacious, and patient.

And likely very wealthy. However -- pinning the argument on me here -- I'm with @Charlie from wmass , and I dare say that he isn't stupid, though I may be. And the bottom line of the place I care for is that Cedric is sized somewhat larger (thank you for the numbers, by the way, @Charlie from wmass ) than the EDR of the installed radiation. And it works. The question I am still left pondering is: is there a way, other than a rule of thumb, for a conscientious installer to figure the needed (clearly needed, to make it work properly) excess size of the boiler, and if so, what are the variables which need to be considered?

I might add that radiation capacity in excess of the design heat loss of the building is also required, so that the temperature can be raised in the event that it falls for some reason -- but that is a completely different matter, and mustn't be confused with the problem under discussion here.

ChrisJ

Jamie, you named your boiler?

DanHolohan

Doesn't everyone? ;-)

Charlie from wmass

Obviously I'm not feeling very well today because I couldn't agree with you more Hatteras guy. Lol

Charlie from wmass

A boiler that can run at 100% on the design day without going through vent gymnastics is the epitome of perfection, @Hatterasguy thanks

DanHolohan

It's nice when there's peace in the valley.

Charlie from wmass

On sizing of edr. I think it is HB Smith column radiators where a 38" 3 columns are 1/2 a square foot per section larger the industrial standard. This is a big deal unless you have 40 of them in a building. I was fortunate enough to catch that before the boiler what sized.

DanHolohan

To build pressure, you have to fill the system with a gas (air and/or steam), and then add more of either. A well-vented and properly sized system can heat with a pressure so low most gauges won't sense it. Perhaps that's what's happening.

Charlie from wmass

Okay dumb question has anybody timed the gas meter? And confirmed combustion efficiency?

New England SteamWorks

1. I think it would be helpful to quantify the problem ( assuming there is one) first.

If we assume no one here uses a pickup factor larger than 1.33, what does Chrisj recommended on the low end? 1.00? Okay, let's assume 1.00. Now let's change the discussion a bit to: What is gained and what is lost between 1.33 and 1.00? Especially when considering that boilers only come in so many sizes?

KC_Jones

Hatterasguy said:

I'm going to have to check that out. The building definitely has some 38" three column rads in all the bedrooms. The building has about 12 of them. But, even with that error, I don't see the pickup factor dropping below 1.3. You'd think it would build pressure at that point.

KC has the same situation.

Yes my true pick up is actually more than the 1.33. I honestly should have gone for a boiler one size smaller, but what I have is fine. I don't typically build any pressure unless it's really cold out and I get longer run times, but the EcoSteam controls the burner run times so that limits things as well. I honestly think I could run with almost no pickup factor. My mains are incredibly short and half of each one is 1 1/2" pipe. Total connected EDR is 265. The system is very small.

Something else to ponder for everyone. Say you have 2 house with the same square footage and the same connected load (EDR). Let's say one is a 2 story and one is a ranch. The ranch would obviously have to have more piping in the basement and the 2 story would have more piping for run outs, but those would be exposed in the house (first to second floor). By current standards both houses get the same size boiler correct? The reality is the 2 story would not need the same pickup factor would it? Just another concept to add to the discussion.

Charlie from wmass

So does that mean that counterflow system would require less of a pickup Factor then a two pipe steam system because there's less Mass to be heated up each cycle?

KC_Jones

I think that is the question isn't it?

ChrisJ

Seriously guys?

Jamie Hall

Perhaps (says he, thinking to stir the pot a bit) it is more our terminology that is misleading? We sort of assume that "pickup factor" is somehow related to trying to get things up to speed from a more or less cold start. But... what if what we are really seeing here is a factor to be applied to the apparent EDR? I think we all agree that one does need to have adequate venting -- after all, the air does have to get out somehow, unless you are running a vacuum system -- and that one does need to have the pipes well insulated (but is that really for preventing the heat loss, or is it more to prevent or reduce condensation and related problems in the steam mains? Hmm...) but, beyond that, as @RI_SteamWorks noted, we find that there is a satisfactory range of operation which seems to be between about 1.33 and 1.00 times the apparent EDR, and we have examples of systems which run happily at both ends of that range, with little or no cycling on pressure but with filling the radiation under extreme conditions.

Are there, then, other things that play into the needed BTU input? The sheer length and size of the steam mains has been mentioned. The presence of unheated risers has been mentioned. The uncertainty in the actual calculation of EDR has been mentioned. Others? Could the accumulated impact of these be what we are really looking at?

KC_Jones

Perhaps it was as simple as the dead men didn't want to take the time to add up all the piping in the entire building and figure out what was needed?
Now imagine if that was true, what are they thinking of our conversation from the other side?

Edit: This is sarcasm.

ChrisJ

@Jamie Hall Remember, the original term was "piping and pickup factor"

The pickup factor is used 100% for raising the temperature of a cold building.

The piping is piping losses.

The 33% is the two combined.

DanHolohan

Pick-up is to allow for the piping to get hot from a cold start. The Carbon Club came up with the idea on December 19, 1889, the same day they decided that steam systems should not exceed 2 psig, and hot-water systems should not run hotter than 180 F. It was a mandate for the members. The Carbon Club eventually became IBR. The group that became ASHRAE took their lead from them.

PMJ

How about we say pickup factor is the extra just in case.....

There seems to be a great fear of extra hardware when in fact it is the lack of it that makes installation and balancing much more difficult as several folks have already observed in this thread. Elaborate (and I admit quite beautiful) headers are being created now to dry steam that used to just come out of the boiler drier from a huge steam chest. I can say from personal experience that big solves many problems. My boiler is clearly not piped "correctly". Bull head T and no equalizer. But the chest and pipes are so big it makes no difference. The steam is dry and I can move a ton of steam at almost no pressure at all.

At the end of the day control is the issue, and the things the control must handle are the same whether the boiler has extra capacity or not. I think those of us with more sophisticated controls can agree that the control is the bigger reason our systems run well - not the size of the boiler. If watching your boiler approach 100% operation in your already warm house as the outside temperature drops toward the design day number makes you feel perfect I say great. It makes me feel great to see mine at only 50% on that day and know I have all that extra just in case. Personal choice. I am quite convinced I give up nothing on efficiency due to the extra - or surely not enough to convince me not to have extra capacity available.

Where I think the effort should go is into affordable controls to improve the general situation out there.

ChrisJ

PMJ said:

How about we say pickup factor is the extra just in case.....

Ok, I'm fine with that.
Wouldn't this be the same as guys installing oversized hot water boilers or air conditioners just in case?

My question isn't suggesting you're wrong in sizing, or that I agree with boilers matched exactly to design day.

I just feel that having extra just in case is no different with steam than it is hot water baseboard or radiaint, forced air or air conditioning.

PMJ

ChrisJ said:

PMJ said:

How about we say pickup factor is the extra just in case.....

Ok, I'm fine with that.
Wouldn't this be the same as guys installing oversized hot water boilers or air conditioners just in case?

My question isn't suggesting you're wrong in sizing, or that I agree with boilers matched exactly to design day.

I just feel that having extra just in case is no different with steam than it is hot water baseboard or radiaint, forced air or air conditioning.

Actually, I think it is different than air conditioning. Air conditioning is primarily dehumidification and only a little bit about cooling. In order to dehumidify you need to actually pass lots of air from the structure through the cool coils. This means the unit must run a high percentage of the time. If it is too big and cools the temp too fast then it turns off and the air is still too wet and you get cold and clammy. So there is a big downside to an air conditioner that is too big. Those really need to miss on the small side.

Boilers can just be shut off and/or run in pulses as I do. All the air in the structure does not need to be "processed" thru the machine.

ChrisJ

PMJ said:

ChrisJ said:

PMJ said:

How about we say pickup factor is the extra just in case.....

Ok, I'm fine with that.
Wouldn't this be the same as guys installing oversized hot water boilers or air conditioners just in case?

My question isn't suggesting you're wrong in sizing, or that I agree with boilers matched exactly to design day.

I just feel that having extra just in case is no different with steam than it is hot water baseboard or radiaint, forced air or air conditioning.

Actually, I think it is different than air conditioning. Air conditioning is primarily dehumidification and only a little bit about cooling. In order to dehumidify you need to actually pass lots of air from the structure through the cool coils. This means the unit must run a high percentage of the time. If it is too big and cools the temp too fast then it turns off and the air is still too wet and you get cold and clammy. So there is a big downside to an air conditioner that is too big. Those really need to miss on the small side.

Boilers can just be shut off and/or run in pulses as I do. All the air in the structure does not need to be "processed" thru the machine.

Good point.
So A\C aside, would you agree a large pickup factor on a steam system is no different than the same with hot water?

ChrisJ

Hatterasguy said:

DanHolohan said:

To build pressure, you have to fill the system with a gas (air and/or steam), and then add more of either. A well-vented and properly sized system can heat with a pressure so low most gauges won't sense it. Perhaps that's what's happening.

The question that begs is why a system that is 40% oversized as compared to the EDR calculation will not develop more than about 2 ounces even if you ran it for one full hour?

In theory, this is impossible unless the rads are delivering far more than the calculated EDR.

The only answer (short of an error in the EDR calculation by multiple people) is that the EDR is variable depending on the water content of the steam. This is quite a statement and would be a game changer if it could be proven. It would terminate all discussion about pickup factors as the boiler could never cycle on pressure with a standard (1.33) pickup factor.

I think it also depends on where pressure is being measured.
At the boiler should be the greatest amount, but also an area where how the boiler's piped and water quality will greatly effect it.

Using too much Steamaster raised my pressure from 1" at the time to over 8".


In my opinion, the way EDR is measured and boiler output is what's questionable. Also the cooler the room, the greater the output from a radiator. Your theory about water content doesn't hold any water IMO. You're transferring energy one way or another, if there's too much there's too much it doesn't care what form it's in.

To me, that means either the radiation is wrong, or the boiler output is wrong, or both. There's really not much else to go by.

ChrisJ

Hatterasguy said:

ChrisJ said:

Hatterasguy said:

DanHolohan said:

To build pressure, you have to fill the system with a gas (air and/or steam), and then add more of either. A well-vented and properly sized system can heat with a pressure so low most gauges won't sense it. Perhaps that's what's happening.

The question that begs is why a system that is 40% oversized as compared to the EDR calculation will not develop more than about 2 ounces even if you ran it for one full hour?

In theory, this is impossible unless the rads are delivering far more than the calculated EDR.

The only answer (short of an error in the EDR calculation by multiple people) is that the EDR is variable depending on the water content of the steam. This is quite a statement and would be a game changer if it could be proven. It would terminate all discussion about pickup factors as the boiler could never cycle on pressure with a standard (1.33) pickup factor.

I think it also depends on where pressure is being measured.
At the boiler should be the greatest amount, but also an area where how the boiler's piped and water quality will greatly effect it.

Using too much Steamaster raised my pressure from 1" at the time to over 8".


In my opinion, the way EDR is measured and boiler output is what's questionable. Also the cooler the room, the greater the output from a radiator. Your theory about water content doesn't hold any water IMO. You're transferring energy one way or another, if there's too much there's too much it doesn't care what form it's in.

To me, that means either the radiation is wrong, or the boiler output is wrong, or both. There's really not much else to go by.

For your statement to be valid, the radiation error would have occurred by multiple people. The boiler input is measured and confirmed. The output is assumed from the boiler efficiency.

The boiler output is measured and confirmed by who?
Both Tim M and Jim D say the combustion efficiency of most of these boilers is 69-79% and that the AFUE rating adds fluff into it for things that reduce stand by losses. If you're only getting 79% of what you put in out, it can't possibly produce the steam output it claims on the label.

I don't know who is right, but I do know I wouldn't bet my life that a steam boiler produces it's rated output.

As far as the EDR of radiators being off, I was suggesting they're all off. It's a rough guess just like the heatloss of a house.

PMJ

ChrisJ said:

PMJ said:

ChrisJ said:

PMJ said:

How about we say pickup factor is the extra just in case.....

Ok, I'm fine with that.
Wouldn't this be the same as guys installing oversized hot water boilers or air conditioners just in case?

My question isn't suggesting you're wrong in sizing, or that I agree with boilers matched exactly to design day.

I just feel that having extra just in case is no different with steam than it is hot water baseboard or radiaint, forced air or air conditioning.

Actually, I think it is different than air conditioning. Air conditioning is primarily dehumidification and only a little bit about cooling. In order to dehumidify you need to actually pass lots of air from the structure through the cool coils. This means the unit must run a high percentage of the time. If it is too big and cools the temp too fast then it turns off and the air is still too wet and you get cold and clammy. So there is a big downside to an air conditioner that is too big. Those really need to miss on the small side.

Boilers can just be shut off and/or run in pulses as I do. All the air in the structure does not need to be "processed" thru the machine.

Good point.
So A\C aside, would you agree a large pickup factor on a steam system is no different than the same with hot water?

I have no experience with hot water and have never thought about it beyond that I'm glad to have steam instead so I won't make an uneducated comment.

BobC

EDR of a radiator is determined by the surface area, the temperature of the fluid (steam or hot water) in a 70F room. If those conditions are met the EDR sb pretty much a known factor, if any condition changes the EDR will follow it.

http://www.columbiaheatingsupply.com/page_images/Sizing Cast Iron Radiator Heating Capacity Guide.pdf

Bob

ratio

I think you guys are missing the point wrt the pickup. Some things are known (relatively) precisely, say connected EDR, and net output. Some things are reasonable guesses, like building heatloss. But some things are unquantifiable. Just how fast is "heats fast enough"? To how many decimal points do we calculate "works fine"?

Perhaps can start rating boiler installs in callbacks-per-season? Now that would be quantifiable!

ChrisJ

ratio said:

I think you guys are missing the point wrt the pickup. Some things are known (relatively) precisely, say connected EDR, and net output. Some things are reasonable guesses, like building heatloss. But some things are unquantifiable. Just how fast is "heats fast enough"? To how many decimal points do we calculate "works fine"?

Perhaps can start rating boiler installs in callbacks-per-season? Now that would be quantifiable!

Just fast enough that the house maintains a steady temperature. In other words, slow.

That's my opinion, ask 10 other guys and you'll get 10 more.

New England SteamWorks

Time for a little Don Rumsfeld?

...because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns – the ones we don't know we don't know.

BobC

Rumsfeld and McNamara were their eras deplorables.

Bob

Charlie from wmass

@BobC I thought it was Obama who was born in Africa, those guys were born in 'MericA.

DanHolohan

Guys. Politics? Really? Please.

BobC

@Charlie from wmass They were both responsible for a lot of men getting wounded or killed because of their stubbornness. Both men served in the armed forces and yet they both pushed policies that pushed up our casualty count; the deporable part is they did it to prove a point.

Cheney did the same thing but at least he never wore a uniform (because he was otherwise occupied), so some ignorance could be understood.

Bob

Charlie from wmass

Sorry, low hanging fruit @Dan Holohan . I will be over in the corner in time out.....

@BobC it was a joke switching deplorable with deportable.

DanHolohan

Please keep it on topic, as Erin has asked us to do. We're discussing pick-up factors here. Please don't hijack Jamie's thread, which is a good and thoughtful one.

Thank you.

Erin Holohan Haskell

Thanks, @DanHolohan. Agreed.

Let's get this back on track, Wallies. Thanks!

Charlie from wmass

Any of the engineers involved can attest to the fact that there are no unknown quantities in the heating systems or the building envelope. Given enough time all of this data can be compiled. But the standard practice of using a pickup Factor allows us to have a boiler size that will work without sleeping days and compiling Links of various sizes of pipe, quantities of fittings, masses of Radiators, and volumes of air that need to be displaced. When one amasses all that data that data you can read now find exactly the size of boiler you would need. But for most situations we have passed the point of diminishing returns.
If one were to size the steam boiler to the heat loss of the building and used a two pipe system with orfices you could balance the system to function properly as David Brunnel has shown.
With a single pipe system it is more tedious to get a long term balance especially as the systems get larger. They are like large mobiles, touch radiator 14 then 22 and 3 over heat and 42 under heats. And a week of sunny wether gets all the steam migrating to the north side radiators and the west side is freezing.
So we compromise. We install a larger boiler and everyone gets heat.
As contractors and engineers I feel our goal is as efficient as practical, not as efficient as possible.
This does not take away from those who are eliminating the envelope. These people are going to give use the next big thing. I hope.

Dave0176

Last winter I installed a boiler that for all purposes was OVERSIZED, I had a connected load of 445 EDR with two additional radiators to be installed, putting me around for 490. I chose a WM EG-55 with 521 sq ft steam. I took a chance by figuring I was also installing a two stage gas valve and building a 4" header, and also removing all insulation in basement piping on the owners request due it becoming living space.

When the install was complete I did spend some time with the homeowner to get it perfect. It rarely seems to cycle on low fire. On the initial startup back in January, (two days no heat house down to 48 degrees) the boiler cycled on low fire after over an hour of running full.

During the coldest times of last year the HO informed me the boiler was running approximately 22-26 minutes per hour, and never once exceeded 8 oz of pressure. The mains heat in 3.5 minutes, so venting is near perfect.

So this does beg, I actually installed an oversize boiler and figured on using the two stage gas valve to lower the rated output, yet it seems to run perfectly. Could it be the 4" header?? Or is it sized ok? I pulled a 660 sq ft oil fired boiler out.

BobC

Having dry steam seems to be a common factor.

Bob

New England SteamWorks

Which brings us back to the unknowns...