electric consumtion of pumps

tom_49

I was on a contractors site recently and they had pix of a radiant job they did. It was a real nice piping job. I then counted 19 ( looked like 007 ) pumps. Thats alot of pumps starting up.

That got me thinking about the electrical consumption of those pumps. 19 pumps x .8 amps, thats alot of juice.

Wouldnt zone valves make more sense towards the whole "system" efficiency.

Thoughts?

[Deleted User]

Better yet...

One circulator for the space heating system with a delta P controller for variable speed operation, and non electric zone valves for the ultimate in comfort and control!

It requires more advanced planning and thought, but what great systems don't?

I agree with the need to reduce parasitic costs of operation. More pumps don't necessairily add up to more efficiency...

ME

THP_6

riggghhhttt

Remember that the man who knows how to pipe the job does not over pump the job. If you think about it the mid range capacity of those 19 pumps is in the range of 150gpm. We are talking 150 GALLONS PER MINUTE. 1,500,000 BTU per hour heat transfer avalable. 9,000 GPH. Isn't that just nuts. I always ask how big is the boiler. Unless your heating 50,000 plus sq.ft. building or so. And to go a step farther you could do all this on steam by moving a mere 3gpm of condensate. That is 50 times less fluid transfer. Maybe thats why I have a problem with how hot water is a big advance forward. But that is just an opinion.

Dave_74

Not a big problem

I do not see this to be a big energy waste. The heat from the electrical energy goes 1.) into the water, and 2.) into the air in the mechanical room. It is not lost. Yes, that part that goes into the room may not get into the house, or it may. Yes, heating with electricity is in many cases may cost more than heating with gas or oil, but the point is, it is not lost.

From a pump use standpoint, this sounds like a lot of pumps, but that is not the main question being addressed here.

Any opposing views??

THP_6

Eff.

What I look at is that your only using the circs. at 10% to 20% of the capacity of whay they are built for. What I give as an example is. If I had to pull a big trailer once a year I would not drive the Semi tractor to work everday. I would drive the smaller car.

Glen

zv vs pumps

I too am in favour of zoning with pumps. But it could be an either/or discussion. In real terms, eg. cost of running a pump on its mid speed at .62 amps x 50 cents KWH vs failure rate of a zv may be a moot point. Just choosing the right zv (read mr Bean's post)in a marginal install where one must push the max gpm to meet load could leave the installer with a long term headache, especially in a retro where the Ho does not want to break eggs to get his omlette. Pumping away almost completely eliminates this worry. Add in other considerations such as glycol and the efficacy of a zv diminishes. Our firm is just finishing a radiant install in Cambridge Bay, Nunavut. Typical glycol levels are in the 40 - 45% range - even at operating temps that's a very viscous fluid - which IMHO calls for pump zoning and nothing else. And at the end of the day, a good multispeed pump like the 15 58, coupled with full port balancing valves makes final flow balancing a snap. Did I always think this way? Not at all - our former standard was one big pump and a handfull of zv's. In the past we also installed air vents everywhere - and now don't put in any except for the vent on the Vitola and one spirovent. I don't believe this is a cost issue - it is an issue of long term comfort for your client. Both strategies work of course - our field experience as shown time and time again - that pumping away makes our job much easier. Which in turn makes for warm, comfortable and superbly happy clients.

hr

Look at the bigger picture

with that multi pumped system, how much work was being accomplished for the amount energy used. Typically the flow rates in those multi zoned residential systems is WAY below the BEP of the circ. On circ can easily handle 4 or 5 1- 2 GPM zones.

Personally I see a lot more seized pump cartridges than bad zone valves And a pump without an ADJUSTED flowsetter makes little sence. rare to see a flowsetter used, much less adjustes, on the large walls of pumps.

Keep both options open, but knowing how and when to chose between the various methods (pump vs ZV)is most important part

hot rod

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Glen

keep both options open -

agreed. Each install offers its own challenges.

THP_6

hot rod

Thanks. I am sure this topic is not over yet. But out of time for now. This was a ill pumped system, now trouble free. Piping and velocity is what is over looked.

Ron Schroeder

If I had zoned my own house with 007 pumps, I would not need a boiler for space heat. The btu output of the pump motors alone (12 zones) would supply my house's heat loss at 0 degrees F. Instead, I have 2 pumps. A 007 for the indirect and a very high efficiency variable speed pump for all of the heating zones.

I am using TACO ESP and Danfoss zone valves which draw 3 watts or less each (lower than most zone valves and a lot lower than pumps). The btu per doller of electricity is much higher than the btu per dollar of oil so my operating cost is less than if I had zoned with pumps.

Ron

Ron Schroeder

It is very hard to heat my basement floor above 55 degrees. I believe most of the heat leakage in the basement is lost.

hr

And a good flowsetter to boot

there is a difference in quality and features of flowsetters. You get what you pay for!

I have never understood the concept of balancing with a ball valve. A partially closed ball presents a sharp edge (wear point) to fluid flow. A cone shaped like Danfoss, T&A and a few others seem a lot more controllable.

Hard to make fine adjustments with a ball valve, if you have ever tried to balance radiant manifolds you will know

hot rod

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Tundra

The Grundfos 15-58 draws 60W at low speed which is enough for most residential zones. Most systems I see are between 3 and 6 zones. Through most of the year you would rarely have more than one zone calling anyway and if one of those zones was an indirect you would probably have a dedicated circulator for that anyway. Most of my competitors use the Honeywell zone valve. I know because I change them out regularly. We have high glycol percentages (40-45%) and the honeywell zone valves tend to go out far more often than circulators. For the cost of parts and labor to replace a zone valve,you can run a circulator for a long time. With circulators sharing the run time and at the slower speed circulators should last a very long time. When I factor in maintenance I see no cost savings in zone valves and indeed, over the life of the system I believe total operating cost to be higher.

thp_7

If you look back in time just a few years when did all the fancy high dollar air elimination products come out? They came out because people stoppped piping the jobs correctly and started having flow / velocity problems. In turn the big fix from the pump company standpoint is to pump the zone. This is not domestic water system, all we need to do is circulate the water around the system. If you need any more than a $10.00 camel back and a $4.00 air eliminator you did something wrong. The point here is, if you do proper pipe design, even in a retro fit job, design the circ. close the max. heat transfer needed to cut the job. This will always keep energy costs at a minimum. And for having redundancy in a system with more pumps, it only takes any one part to stop the system. ie: $3.00 thermocouple or lose wire nut.

Paul Pollets

Less is More...

Using modern valve bodies (with unions) and slow-acting snap-on solenoid heads, most zone valves are reliable and much more efficient than zoning with multiple pumps... As long as the pump is installed with a pressure bypass differntial. Why waste 3000w when you only needed 150??? Why be pushing 10gpm when only 1gpm is needed?



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