Pump sizing

TahoeT

Hi and thanks in advance to reading my question. I have a home in Reno nv that I am wanting to finish installing the hydronic system.
We remodeled and installed 1/2 tubing in gypcrete on the original slab in the 1200 square foot great room, there are four 500' 1/2" runs connected to a manifold.
The rest of the runs are under the floor ply in joist bays.
The two bedrooms will be 300' 1/2" runs each and the playroom will be two 300' 1/2" runs.
The master and guest bath are on a 400' 1/2" run.
In the master I am looking at Rescom slim baseboards.
I have purchased a phe 130/55 versa hydro to run both radiant and DHW.

I am looking for any help/suggestions on pump size and preferred brand.
The calcs I come up with are not working do to the long runs, btu heat loss of the old slab and delta T not determined.
I also would invite any suggestions of knowledgeable consultants in my area. I would love to have someone come adjust and balance the various units.
Thanks again

Gordy

With the length of those loops......big...... 1/2" pex should be no more than 250' 300 at most.

Floors,delta,shoot for 10* baseboard 20*.

Need more info. Zoning?
If zoning how are the zones broke up?

TahoeT

Yes unfortunately they are long but set in stone. The zones will be one large great room, each bedroom and the play room individual. I could separate the great room into multiple zones if it would help. I understand the system will not be optimal, but anything will be better than my forced air fighting a cold slab all winter.

Gordy

First question before the Circs.

Was a room by room heatloss done? Because with out that we can not begin.

Gordy

Are you planning to zone with pumps, are zone valves?

Gordy

As for a consultant. I think it would be a good idea. Go to find a contractor on this site punch in your zip code.

Tinman

The "other runs under the ply in joist bays" - were heat transfer plates used with the tubing?

TahoeT

I am planning on zone valves, though I have been finding mixed thoughts to pumps vs valves, please share yours. I have a very basic heat loss to satisfy for building permits and I have done a basic manual j but I would like to have a real calc done by a qualified person. I will check the contractor section thanks.

TahoeT

Heat transfer plates were used.

Gordy

You will be looking most likely at different water temps for the plated install verses the gypcrete. With out a detailed heat loss it's all guessing.

The heatloss for each room will provide the information needed to calculate flow rates, water temps to achieve the desired floor temps to off set the load for the particular room. Then you can size a circulator.

With the erratic loop lengths, and not knowing how everything is piped. You might be better off zoning with circulators. At first thought.

TahoeT

Thanks for the thoughts, I will update when I know more.

Paul48

I'd split those monster 500' runs, even if I to use baseboard enclosures to hide pex.

Tinman

They're in poured concrete.

TahoeT

Is there any reason to separate the long runs and put a pump on each one to help with the head? Would it help or is it possible to put a push and a suction pump at both ends of the large zone?

Gordy

There is a 4 way reversing valve that can do this.

The goal is minimum pump size for efficiency. Also hard to get even floor temps with long loops.

TahoeT

I am looking at the grundfos 26-120 or26-150 but thought I could maybe put an alpha on either end if that even works or not. I imagine I will have uneven heating though if I can get the floor temp up with relatively low cost I would be able to supplement with my forced air furnace I am using now. Maybe even look into aN air handler off the boiler. If can save any on propane costs and bring the floor to a comfortable temp I would be happy. Right now I have a 120btu 90%plus furnace that runs quite often, about 200 gallons a month to keep it around 67* and our floor is cold and upstairs is hot.

Gordy

As stated earlier. You need to know the heat load for each of the rooms. Then you can size a circulator. We don't know if you need .5 gpm, or 1 gpm per loop.

Example: pex a at .5 gpm is 5 feet of head for a 500' loop
1 gpm is 19 feet of head for a 500' loop

Sounds reasonable except at those flow rates you will never get a 10* delta for even floor temps. Doubt if you could get 20 or 30

What centers is the tubing lay out?

TahoeT

After much discouragement about my 500' runs i dug out my paper work I made when laying the tubing. It turns out I have 300' runs.
Good news for me, sorry to waste your time on the wrong specs. Any suggestions now?
I was originally looking at the grundfos alpha 15-55
Though with +-20' of head, I'm not sure if it would be enough.

Gordy

Here is an example:

Let's say the rooms heat loss is 15000 btus.

If I have 3 loops each loop needs to provide 5000 btus.

At a 10* delta I would need 1 gpm to get 5000 btus.
At a 20 * delta I would need .5 gpm to get 5000 btus.
At a 30 * delta I would need .34 gpm to get 5100 btus

Gordy

TahoeT said:

After much discouragement about my 500' runs i dug out my paper work I made when laying the tubing. It turns out I have 300' runs.
Good news for me, sorry to waste your time on the wrong specs. Any suggestions now?
I was originally looking at the grundfos alpha 15-55
Though with +-20' of head, I'm not sure if it would be enough.

What about the 400'?

Yes that is good news.

TahoeT

Yes I need a good heat loss done, ASAP. I am just trying to get as much info/knowledge as I wait.
My layout is from the exterior into center, back and forth.
I image the delta t will be 20-30 as the old slab has no insulation, but I am adding 2.5" foamular to the exterior foundation.

TahoeT

All are 270'-300'

Brewbeer

You can do the heat loss yourself. It's not terribly complicated, but it does require you to accurately measure the area of all the various exterior surfaces in each room (windows, walls, ceilings, floors, doors, etc.), determine r-values, and apply design parameters. A spreadsheet works very well at managing the calculations and allows you to easily make changes.

Brewbeer

Wait - the zone on the concrete slab doesn't have insulation under it?

Gordy

TahoeT said:

Yes I need a good heat loss done, ASAP. I am just trying to get as much info/knowledge as I wait.
My layout is from the exterior into center, back and forth.
I image the delta t will be 20-30 as the old slab has no insulation, but I am adding 2.5" foamular to the exterior foundation.

What centers did you lay the tubing? 12" 9" 8"6"?

TahoeT

The tube is 12" on center. I am willing to do the heat loss but I have not been able to find a way or site to do it, I don't just want to purchase a program not knowing if it's going to do what I want. I did a basic calc on a site called loadcalc.net but I would like to have a real one done.

TahoeT

The numbers from the site work out to be 63000 btu at 0* exterior temp. Does that seem reasonable for a 1500 square foot great room?

Gordy

No, but anything is possible. Lots of glazing, and multiple exterior walls? if it is which I doubt. You would need supplemental heat. Expect 30 btus a square foot for radiant floor output 35 tops. 45-50 k.

Brewbeer

If you are handy with a tape measure and a spreadsheet you can do a quite accurate heat loss calc.

bmwpowere36m3

Try SlantFin program... takes a little skill, but its free and my calcs worked out fine when I was planning my system.

http://www.slantfin.com/professionals-page/heatloss.html

You could also post some details on the room and maybe one of us could run it.

Rich_49

Do not forget to add the head through the HX of the Versa Hydro to your calculations or you will be in trouble .

Pri / sec is a good idea on some occasions when using the Versa , dependent on what you are trying to accomplish . Radiant floors and a 10* Delta on the system side and a 20* Delta on the flat plate side is one of them . The circ that is installed onboard and the programming of the unit really want to see a 20* delta at the flat plate .

TahoeT

I will have the time this weekend to go through a more thorough heat loss, thanks for all the suggestions.
Rich , It sounds like you have first hand experience with the versa. What is your opinion on the units? I would be interested in talking to you if you have the time, I am willing to compensate you if it is needed.

Rich_49

Feel free to use my contact information . Old fashioned phone conversations save alot of time and prolong the requirement for carpal tunnel treatment .

Steamhead

Rich said:

Old fashioned phone conversations save alot of time and prolong the requirement for carpal tunnel treatment .

+1 !