Circulator pump sizing. Will the 007e-f2 work?

Trevcaru

I am trying to figure out which circulator to go with...
Here are my specs:

2,300 sq ft house 
dedicated Tankless water heater on a closed loop
62,000 BTU heat load
1/2" pex @ 300 ft loops
10 loops
planning 2 zones


Will a single TACO 007E-F2 007 ECM HIGH-EFFICIENCY CIRCULATOR suffice?

Will i need multiple pumps?

Can/should i make my loops shorter and buy a corresponding manifold?

I have options as the system isnt completed yet.
I have bought the 007e-F2 already and im not certain i should i should install it.Thanks in advance.

Ironman

I'm glad you came here because you'll get the best advice possible on radiant heating.

Please allow me to ask some questions and suggest some things about your proposed system.

First, I see you have a load calculation. Can you tell what method was used to get the 62k btu number. This is very important because an ACCURATE load calc is essential. It's the foundation for PROPERLY designing everything in the system - including pump selection. I've done load calcs for well over 35 years and that number seems a little high for new construction. Unless your in AK, MN or ME. It comes to almost 27 btus per sq. ft. and most energy codes require that the house be constructed to achieve less than 25 btus per sq. ft.

Second, please be aware that a tankless water heater is the wrong appliance for space heating. It is not approved, designed or controlled for that. The heat exchanger in it has a huge pressure drop that standard hydronic circulators cannot overcome. Think about it: if a tankless water heater could take the place of a boiler, there would be no need to make boiler's. You need a boiler, not a water heater. I know, a boiler costs more. But you're gonna find that the laws of physics out-weigh the laws of eccomics every time.

Third, do you have an actual design? You total tubing, it's spacing and other factors indicate that you will not be able to get the 62k btus that you calculated. You need to have a good workable design. Got a diagram or any calcs that you could post?

Trevcaru

Thanks Bob,
I did the manual J heat loss calculations using Loopcad. Looking back, i made some mistakes. Here is a new report (see attached). Does this sound more accurate? It is not new construction, but it has been vastly updated with half the walls being 2x6, part of the ceiling is R38 where i vaulted it, and the basement has insulated walls and will have some xps on slab.

The SQ footage is 2,186
Heat load is 38,000

Zman

The 007 would be maxed out doing just the loops. If it had to push through a tankless water heater as well it won't work.
I seems like a lot of folks trying to heat their house with a water heater this week. What gives?

PatrickHennessy

I'm also curious about the Taco 007e sizing. I have a 3100 sqft house with 1 Taco 007e for the heat. Indirect on it's own 007e. Is that adequate? My contract or says it can handle several zones. Most pics of newly installed systems show circulators on each zone.

Dave H_2

The 007e is MORE than enough circ based upon some rough numbers I put together.
38,000 BTU heat loss
10 loops
3,800 btu's per loop
300' loops
120F water temp
15 degree delta T

That shows a 0.5 gpm per loop flow rate
at 0.5 gpm, the head loss is 3.66 ft of head
The total circ needs are 5 gpm at 3.66 ft of head.

This head loss calc does not include the pressure drop associated with any other components like the manifold(s), mixing valve.....
Some assumptions in mixing, using the i-valve, a 1" thread model has a Cv of 3.0 will add an additional head loss of 6.4 will then will change the circ requirements to 5 gpm at 10 foot of head.
Change the valve to a 1" union version and the Cv more than double to 6.6 and the new head loss is 1.3 additional foot of head to change the circ to 5gpm at 5 foot of head.

All three scenarios are fine for the 007e. In the pic attached, the "X" is the first scenario where the design is, the blue dot is where it will actually work (about 9pgm at 9 foot of head)

Dave H.

Dave H_2

and @PatrickHennessy You should have more than enough circ, see previous example

Dave H.