# Primary Secondary - heat loss, flow rates & water temps

### Primary Secondary - heat loss, flow rates & water temps

OK, so I've been reading my new books by Dan Holohan and I've been putting the specs of my system together so I can try to design my new primary/secondary system with the proper pipe size, pump size, and flow rates.
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1. My house is 1 zone ~100' of 3/4" fin baseboard. @600 BTU/ft that equals ~60,000 BTUs. Now since the baseboard is 3/4" I'm limited to 4 GPM for copper.

Using BTU/(delta T x 500) = GPM

GPM = 4
BTU = 60,000

and the calculated delta T is 30F.
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2. I have an Amtrol WH-7P 41 Gallon Boilermate Indirect HW heater that has a 140,000 BTU heat exchanger. The company specs say to use 5 GPM flow.

so
BTU = 140,000
GPM = 5
so the calcluated delta T would be 56F
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So far at worse case scenarios of 1 and 2 together say I need 9 GPM of flow.

Here's where I get confused.

3. The KA-4 boiler specs:

BTU gross: 96k
BTU net: 81K

Using the above formula

BTU = 81,000
Delta T = 20F

the calculated GPM is 8.1 GPM. Or if I change delta T from 20F to 40F the GPM drops to 4.05.

Does that mean that if I use a delta T of 20F then the most GPMs the boiler circuit and the primary circuit should be is 8.1 GPM?

That's part 1 of my work.

Part two is that we are putting on an addition to our house and will be installing Radiant Heating in that portion. We also may remove the baseboard and do the whole house with Radiant. But let's not bring that into the mix quite yet.
beatle78

Stove/Furnace Make: Keystoker KA-4

### Re: Primary Secondary - heat loss, flow rates & water temps

100 feet of 3/4" baseboard in one zone or loop?? I would think that is about twice as long as it should be.. Did you have low water temps in the return side in cold weather??

Any way you can split the 100' into two zones??

Greg L.

.
LsFarm

Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

### Re: Primary Secondary - heat loss, flow rates & water temps

LsFarm wrote:100 feet of 3/4" baseboard in one zone or loop?? I would think that is about twice as long as it should be.. Did you have low water temps in the return side in cold weather??

Any way you can split the 100' into two zones??

Greg L.

.

Yes I do! But they are the 2 bedrooms and a litter cooler never seemed to matter to us. Of course the last time we used the baseboard, we had no kids! Now my daughter sleeps in the last room on that 100' stretch. Perhaps it will get too cold for her in there now.

I could easily split that loop 1/2 way through BUT we still haven't ruled out converting the house to radiant heat when we do the addition, so I didn't want to do too much work for nothing
beatle78

Stove/Furnace Make: Keystoker KA-4

### Re: Primary Secondary - heat loss, flow rates & water temps

I almost hate to suggest this but, buy another book:

http://www.hydronicpros.com/publication ... .php?id=24

I comes with software to specifically design zoned baseboard system exactly like yours. Also how to size your expansion take. Plus your planned radiant heat. Highly recommended.
Yanche

Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

### Re: Primary Secondary - heat loss, flow rates & water temps

Thanks Yanche! I may have to do that.

Question, is it really the book that I need or just the design software that comes with it?
beatle78

Stove/Furnace Make: Keystoker KA-4

### Re: Primary Secondary - heat loss, flow rates & water temps

Hi Yanche,

What features are "missing" from the academic version of Hydronic Design Studio?

What can I do and what can I NOT do with this version?

Thanks,
Jeremy
beatle78

Stove/Furnace Make: Keystoker KA-4

### Re: Primary Secondary - heat loss, flow rates & water temps

The book is what you need. The included software is the limited functionality version of the author's professional full up software. It can only do the simple things like baseboard, expansion tank, circulator selection and anti-freeze calculations. What it does can be used any number of times, there is not limit like with some trial software.

All the formulas and equations are in the book to do everything, primary-secondary, radiant heat, snow melt, heat loss calculations, etc. It's the only book you need. There may be a paper back cover of the book that's a little less expensive. Mine is hardback and was about \$125. The paperback may not come with the softwater, check before ordering.
Yanche

Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

### Re: Primary Secondary - heat loss, flow rates & water temps

beatle78 wrote:
I could easily split that loop 1/2 way through BUT we still haven't ruled out converting the house to radiant heat when we do the addition, so I didn't want to do too much work for nothing

Beatle,
If the new addition is going to be on it's own zone then you really wouldn't be doing any wasted work to convert the baseboard into a radiant floor system now. It might save you some of the trouble you are going through trying to figure out how to combine the two systems together. I'm sure the new addition with have the radiant floor installed from on top of the floor while the baseboard section is going to have the radiant floor installed from underneath in which case you may want them on two different zones as they are each going to heat up a little differently.

Stove/Furnace Make: Chubby Sr. Old School

### Re: Primary Secondary - heat loss, flow rates & water temps

I see nothing wrong with your calculations!

your question: Does that mean that if I use a delta T of 20F then the most GPMs the boiler circuit and the primary circuit should be is 8.1 GPM?

YES! But then I never designed from scratch or did my own flow calculations because I was a grunt on new install jobs or came in to fix things that the smart guys couldn't.. My installations have been done with scrap or the salvage of the legacy system.

I am a simple vigil ante wet guy! In that - I make Delta T during operation by opening or choking flow in the loops and balancing the system. Once that is done the system just works - or it don't - because the boiler is too small or the load is too big.

If you did your heat loss calculations - and this appliance has the capability to meet the projected demand -- its all good.
Sting

Other Heating: BurnHAM=NG-gas

### Re: Primary Secondary - heat loss, flow rates & water temps

Sting,

I never thought about using ball valves to limits the flow on certain branches to "fine tune" them! nice! I seem to recall Greg mentioning that to me last fall when I was trying to figure out how to hook up the hot water coil in my stoker stove.

Here is a nice calculator for figuring head loss.....

http://www.engineeringtoolbox.com/hazen ... d_797.html
beatle78

Stove/Furnace Make: Keystoker KA-4

### Re: Primary Secondary - heat loss, flow rates & water temps

Yanche wrote:The book is what you need. The included software is the limited functionality version of the author's professional full up software. It can only do the simple things like baseboard, expansion tank, circulator selection and anti-freeze calculations. What it does can be used any number of times, there is not limit like with some trial software.

All the formulas and equations are in the book to do everything, primary-secondary, radiant heat, snow melt, heat loss calculations, etc. It's the only book you need. There may be a paper back cover of the book that's a little less expensive. Mine is hardback and was about \$125. The paperback may not come with the softwater, check before ordering.

OK, thanks Yanche!
beatle78

Stove/Furnace Make: Keystoker KA-4

### Re: Primary Secondary - heat loss, flow rates & water temps

beatle78 wrote:
I could easily split that loop 1/2 way through BUT we still haven't ruled out converting the house to radiant heat when we do the addition, so I didn't want to do too much work for nothing

Beatle,
If the new addition is going to be on it's own zone then you really wouldn't be doing any wasted work to convert the baseboard into a radiant floor system now. It might save you some of the trouble you are going through trying to figure out how to combine the two systems together. I'm sure the new addition with have the radiant floor installed from on top of the floor while the baseboard section is going to have the radiant floor installed from underneath in which case you may want them on two different zones as they are each going to heat up a little differently.

The heating in the new addition is going to be Radiant Slab on grade. We have a walkout basement in a RR style house and the room is going to be off the basement. It will have to be it's own zone. At the same time we're trying to figure out how to heat the rest of our basement slab as this will become finished space also. We're looking into some dry Radiant installations that go on top of the existing slab.

The Baseboard upstairs could stay forever. But I really like all the things I have been reading about Radiant heating and I would like to convert the "upstairs" to Radiant and remove the baseboard.
beatle78

Stove/Furnace Make: Keystoker KA-4

### Re: Primary Secondary - heat loss, flow rates & water temps

The heating in the new addition is going to be Radiant Slab on grade. We have a walkout basement in a RR style house and the room is going to be off the basement. It will have to be it's own zone. At the same time we're trying to figure out how to heat the rest of our basement slab as this will become finished space also. We're looking into some dry Radiant installations that go on top of the existing slab.

Our basement slab was uninsulated underneath it, which they didn't do back in the 80's. So we laid down a vapor barrier along the whole floor and up covering the half walls and sealed it tightly. We installed 1/2 inch form board since we didn't want to loose to much ceiling height, covered it with wire mesh and then laid down our radiant tubes connecting them to the wire mesh and then poured 3 inches of concrete on top of it giving us a very nice warm floor. We then built up our knee walls and spray form the all the walls. It came out very nice.

The Baseboard upstairs could stay forever. But I really like all the things I have been reading about Radiant heating and I would like to convert the "upstairs" to Radiant and remove the baseboard.

We have a raised ranch that we had just bought and it had electric baseboard heat on the first floor. We took it all out and installed staple up radiant floor heating underneath it. We loved the warm floors we had last winter, to bad it was all heated with oil. Once you do it you'll be asking yourself why you didn't do it sooner?

Which is why I asked if you plan on removing it then why not save yourself some trouble from trying to tie the couple different systems together and just go ahead and remove the baseboard and throw up the radiant floor now?

Stove/Furnace Make: Chubby Sr. Old School

### Re: Primary Secondary - heat loss, flow rates & water temps

beatle78 wrote:The Baseboard upstairs could stay forever. But I really like all the things I have been reading about Radiant heating and I would like to convert the "upstairs" to Radiant and remove the baseboard.
Don't sell the proper use of convection baseboard heat short. It's ability to pump out heat under a window is something that's difficult to do with in-floor radiant. Having heat in front of a window overcomes the draft cause by the cold window surface. Rooms with a large window areas and only radiant floor heat feel uncomfortable.

Radiant in floor heat in the lowest floor of a house and convection heating (baseboard or radiator) on upper floors can make a very comfortable home. Radiant in floor heat in selected rooms also make sense. Bathrooms for warm floor reasons and kitchens where it is frequently difficult to find enough wall space for the needed baseboard length.
Yanche

Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

### Re: Primary Secondary - heat loss, flow rates & water temps

The heating in the new addition is going to be Radiant Slab on grade. We have a walkout basement in a RR style house and the room is going to be off the basement. It will have to be it's own zone. At the same time we're trying to figure out how to heat the rest of our basement slab as this will become finished space also. We're looking into some dry Radiant installations that go on top of the existing slab.

Our basement slab was uninsulated underneath it, which they didn't do back in the 80's. So we laid down a vapor barrier along the whole floor and up covering the half walls and sealed it tightly. We installed 1/2 inch form board since we didn't want to loose to much ceiling height, covered it with wire mesh and then laid down our radiant tubes connecting them to the wire mesh and then poured 3 inches of concrete on top of it giving us a very nice warm floor. We then built up our knee walls and spray form the all the walls. It came out very nice.

The Baseboard upstairs could stay forever. But I really like all the things I have been reading about Radiant heating and I would like to convert the "upstairs" to Radiant and remove the baseboard.

We have a raised ranch that we had just bought and it had electric baseboard heat on the first floor. We took it all out and installed staple up radiant floor heating underneath it. We loved the warm floors we had last winter, to bad it was all heated with oil. Once you do it you'll be asking yourself why you didn't do it sooner?

Which is why I asked if you plan on removing it then why not save yourself some trouble from trying to tie the couple different systems together and just go ahead and remove the baseboard and throw up the radiant floor now?

hehe, you make an excellent point. I'm nervous I will run out of time between the addition (not sure when it's gonna start) and putting up the radiant flooring. I didn't want to put up the radiant flooring b/c the 2nd part of our addition involves blowing out our entranceway way 14' and adding a 3 car offset garage on the side of it.

If I put the radiant in now, there will be some floor that has no loop under it.....

On the other hand, I could always use that extra zone from the baseboard to heat a hot tub in the future

That's my dilemma right now..... thoughts?

I'm glad you guys REALLY like the radiant floor! I found a dry system that will only take up ~1" of floor space on the existing slab and includes some insulation as well.
What size tubing did you use in your retrofit of the basement floor.

Yanche,

You make a good point too. Perhaps we will be happy with the radiant downstairs and the baseboard upstairs. The only retrofit we may need to do is break up the upstairs into more zones, and put radiant in the bathrooms.

In the enf the "upstairs in our RR will be only bedrooms and 2 bathrooms. The "basement" will be our kitchen, and the new "sunroom" will be our living room. Keep in mind our basement is at ground level and it walks out to the lake.
beatle78

Stove/Furnace Make: Keystoker KA-4