# Sizing a Boiler for Hydro Air?



## PlumberPete

Does anyone know how to size a boiler for a hydro air system that is already in place? There are 3 air handlers and the building is two stories with a total of 4,980 sq.ft. (5,000). 
Here is the deal. The heat is currently supplied by two 250 HP Industrial Boilers in an Industrial setting. The company is looking two separate the Office building from the industrial buildings.
Any ideas or suggestions here? Thanks.


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## OldSchool

The easy way to figure heat loss is to determine if the building is tight or loose construction and the insualtion and R value of it...

It also depends on the design temperature which would be the average low temperature in the winter... ours is -20 degs C

A more formal way is to use a manual J calculation figuring outside wall surface and ceiling,,, North South east and west along with window sizes and doors. R value of insulation of wall and ceiling.

Typically for our design temperatures up here if I was to do a quick calculation would be any where between 20 and 50 Btu per square ft of heated area.

So your typical building of 5,000 sqft would be 100,000 btu to 250,000 btu heat loss depending on tight or loose construction. 

remember this is heat loss so your equipment has to be larger than the heat loss....

it all depends on input and out put on your equipment or effiency


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## OldSchool

Now what you have is two 250 hp units

1 hp = 2,545 btu

so you have 1.272 Mbtu

That is a lot of Btus for that much area.... so my question is ... what else are they doing with this equipment.... are they also using it to make hot water for something else.


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## PlumberPete

OldSchool said:


> Now what you have is two 250 hp units
> 
> 1 hp = 2,545 btu
> 
> so you have 1.272 Mbtu
> 
> That is a lot of Btus for that much area.... so my question is ... what else are they doing with this equipment.... are they also using it to make hot water for something else.


They produce steam to heat the factory. The thing is that the machinery also produce heat. So they would like to shut the steam boilers down.


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## OldSchool

CardinalPumbing said:


> They produce steam to heat the factory. The thing is that the machinery also produce heat. So they would like to shut the steam boilers down.


That makes a little more sense..... is the intention to keep the steam system or convert it to hot water.


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## PlumberPete

OldSchool said:


> That makes a little more sense..... is the intention to keep the steam system or convert it to hot water.


They are going to keep the steam system for the industrial side and they want a separate boiler for the hydro air in the office building.


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## Protech

WTF is "hydro air"?




CardinalPumbing said:


> They are going to keep the steam system for the industrial side and they want a separate boiler for the hydro air in the office building.


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## Redwood

Protech said:


> WTF is "hydro air"?


Hydro Air uses hot water from a boiler that goes through a coil in an air handler to make hot air which is blown through ducts to provide heat.

Kinda like those central air systems you see in Florida only the coil is hot....:laughing:


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## breid1903

a water or steam to air heat exchanger. breid..............:rockon:


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## Redwood

breid1903 said:


> a water or steam to air heat exchanger. breid..............:rockon:


Yea sometimes steamin hot...


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## ZL700

Besides a heatloss to confirm sizing, take a look at the air handler specs with the specific coil, it will tell you the BTU capacity at a given GPM and water temp. 

For instance a typical 3-ton unit will do 30,000 to 60,000 with 3-6 gpm at 160 degree water, or thereabouts off the top of my head.


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## OldSchool

ZL700 said:


> Besides a heatloss to confirm sizing, take a look at the air handler specs with the specific coil, it will tell you the BTU capacity at a given GPM and water temp.
> 
> For instance a typical 3-ton unit will do 30,000 to 60,000 with 3-6 gpm at 160 degree water, or thereabouts off the top of my head.


1 ton is 12,000 Btu......so 3 tons is 36,000 btu usually tonage is to describe AC units....

usually a coil in an air handler is in BTUs.. the higher the water temp or steam the higher the BTU.

The rating plate would say x amount of btu at x amount of water temp.


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## OldSchool

CardinalPumbing said:


> They are going to keep the steam system for the industrial side and they want a separate boiler for the hydro air in the office building.


So what are your intentions then for the new boiler for the office water or steam. And are you intending on using the existing air handler and piping.

If you intend to convert to water you will have to remove the steam trap on the air handler....


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## ZL700

OldSchool said:


> 1 ton is 12,000 Btu......so 3 tons is 36,000 btu usually tonage is to describe AC units....
> 
> usually a coil in an air handler is in BTUs.. the higher the water temp or steam the higher the BTU.
> 
> The rating plate would say x amount of btu at x amount of water temp.


Duh

The hydronic coils are usually matched to the cooling capacities

Again, once a cooling capacity is chosen, the unit specs will show the heat capacities with various gpm's supplied, along with heating fan speed chosen. 

You've never done a hydronic air handler before have you.


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## ZL700

OldSchool said:


> So what are your intentions then for the new boiler for the office water or steam. And are you intending on using the existing air handler and piping.
> 
> If you intend to convert to water you will have to remove the steam trap on the air handler....


Your not following they wish to not fire the gigantic steam boiler to supply heat to offices only?

Makes perfect sense to give the existing hydronic air handlers their own dedicated boiler to meet this relatively low heat load.


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## OldSchool

ZL700 said:


> Duh
> 
> The hydronic coils are usually matched to the cooling capacities
> 
> Again, once a cooling capacity is chosen, the unit specs will show the heat capacities with various gpm's supplied, along with heating fan speed chosen.
> 
> You've never done a hydronic air handler before have you.


The handler is sized for cfm... that is cubic ft per minute of air

You need a certain amount of cfm in an air handler for the AC to work properly per ton. 

An A coil or an ac coil is not an hydronic coil

I think you have no clue what you are talking about.


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## OldSchool

ZL700 said:


> Your not following they wish to not fire the gigantic steam boiler to supply heat to offices only?
> 
> Makes perfect sense to give the existing hydronic air handlers their own dedicated boiler to meet this relatively low heat load.


I dont think you are following....

The existing system was steam... not water... and I do realize that the intend to replace a boiler at a smaller size to do the offices..... these air handlers are existing..... and they are steam not water

You may have read about systems but I highly doubt you have ever installed one.


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## ZL700

OldSchool said:


> The handler is sized for cfm... that is cubic ft per minute of air
> 
> You need a certain amount of cfm in an air handler for the AC to work properly per ton.
> 
> An A coil or an ac coil is not an hydronic coil
> 
> I think you have no clue what you are talking about.


You still don't get it.

If you go to a manufacturer of hydronic air handlers, you select the AC size desired, then if your not buying a heat coil module, thus the coil is packaged in the cabinet, meaning the air handler has two coils.

Then depending on the AC capacity the AC coil will be a flat angled coil, a-coil, n-coil, and so on.

The preinstalled water/steam coil is typically a flat coil located downstream of the fan. 

Then not being a variable speed unit, the fan will be a 3 or 4 speed fan, giving you choices of CFM for both heating and cooling application.

The heating fan speed affects the AH output combined with GPM and temp of water supplied, and in some cases steam. 

For instance a first company air handler, 3 ton drive (AC) on medium high fan speed, with 5 gpm supplied at 160 degrees will deliver 62,000 Btus of heat with a 25 degree delta t.

I don't know what I'm talking about? Stick to plumbing please.

Remember I'm not the gullible guy almost taken by a 419 scam


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## OldSchool

ZL700 said:


> You still don't get it.
> 
> If you go to a manufacturer of hydronic air handlers, you select the AC size desired, then if your not buying a heat coil module, thus the coil is packaged in the cabinet, meaning the air handler has two coils.
> 
> Then depending on the AC capacity the AC coil will be a flat angled coil, a-coil, n-coil, and so on.
> 
> The preinstalled water/steam coil is typically a flat coil located downstream of the fan.
> 
> Then not being a variable speed unit, the fan will be a 3 or 4 speed fan, giving you choices of CFM for both heating and cooling application.
> 
> The heating fan speed affects the AH output combined with GPM and temp of water supplied, and in some cases steam.
> 
> For instance a first company air handler, 3 ton drive (AC) on medium high fan speed, with 5 gpm supplied at 160 degrees will deliver 62,000 Btus of heat with a 25 degree delta t.
> 
> I don't know what I'm talking about? Stick to plumbing please.
> 
> Remember I'm not the gullible guy almost taken by a 419 scam


Remember... this is not the first time you were wrong as in the gpm in a pipe thread...

First off I am just not a plumber .... we are a full mechanical company....we do plumbing ..heating forced air, hydronic, steam, radiant and AC

Second off I have been doing calculations and design before you were born.

Third off you are just an engineer that never install a single thing in your life.

Fourth ... in your description of tonage when you first mentioned it..... a hydronic coil would never be represented as tonage.....

Fifth..... You started the insults Sonny 

Sixth.... a fan motor is never sized by tonage ..it is HP... try buying a 3 Ton fan motor.... surely you will get laughed at


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## PlumberPete

OldSchool said:


> Remember... this is not the first time you were wrong as in the gpm in a pipe thread...
> 
> First off I am just not a plumber .... we are a full mechanical company....we do plumbing ..heating forced air, hydronic, steam, radiant and AC
> 
> Second off I have been doing calculations and design before you were born.
> 
> Third off you are just an engineer that never install a single thing in your life.
> 
> Fourth ... in your description of tonage when you first mentioned it..... a hydronic coil would never be represented as tonage.....
> 
> Fifth..... You started the insults Sonny
> 
> Sixth.... a fan motor is never sized by tonage ..it is HP... try buying a 3 Ton fan motor.... surely you will get laughed at


Actually the air handlers are hot water. There is a heat exchanger in one of the buildings before the supply and return head over to the office building.


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## OldSchool

CardinalPumbing said:


> Actually the air handlers are hot water. There is a heat exchanger in one of the buildings before the supply and return head over to the office building.


Are your intentions to use a new water or steam boiler?


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## OldSchool

Your best bet would be to go with all hydronic and eliminate the heat exchanger.... the existing heat exchanger is more than likely sized for steam to hot water and would more than likely be under sized for water to water. 

I would use a modulating Buderus Boiler GB142 or 162.... if you use modulating equipment it is okay to oversize the boiler equipment... also better to be safe than sorry.


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## ZL700

CardinalPumbing said:


> Actually the air handlers are hot water. There is a heat exchanger in one of the buildings before the supply and return head over to the office building.


I knew that since smaller residential sized hydronic air handlers rarely have steam coils. Obviously if the steam boiler(s) are used as process steam, it is simpler to use a steam to water exchanger versus reducing steam pressure. 

And yes in your case abandon exchanger to allow steam operation to be reduced, useing a straight hot water boiler of choice.

Thanks for clarification


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## ZL700

Cardinal, Here is an example of a spec sheet from a hydronic air handler company (2 coils, 1 AC, 1 wet).

Notice the size is based on cooling capacity, then the hydronic heating specs fall into line


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## ZL700

OK so word docs wont attach below 200mb

Here is a link:

http://firstco.com/firstcoimages/pdf/hbxb-hw.pdf

(Page 3)


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## ZL700

OldSchool said:


> Remember... this is not the first time you were wrong as in the gpm in a pipe thread...
> 
> First off I am just not a plumber .... we are a full mechanical company....we do plumbing ..heating forced air, hydronic, steam, radiant and AC
> 
> Second off I have been doing calculations and design before you were born.
> 
> Third off you are just an engineer that never install a single thing in your life.
> 
> Fourth ... in your description of tonage when you first mentioned it..... a hydronic coil would never be represented as tonage.....
> 
> Fifth..... You started the insults Sonny
> 
> Sixth.... a fan motor is never sized by tonage ..it is HP... try buying a 3 Ton fan motor.... surely you will get laughed at


Dementia?


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## OldSchool

ZL700 said:


> Dementia?


Go read another book.... or better yet keep up your google search :whistling2:


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## ZL700

OldSchool said:


> Go read another book.... or better yet keep up your google search :whistling2:


It only confirms what I have written from the beginning old man.

My company has installed many of these type of systems. 

FYI, engineers own HVAC companies.


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