Grundfos Alpha opinions

[willworkforwood]

This is general plumbing/heating rather than a boiler question, but it relates to system efficiency, and I think others on the forum may be interested in the subject. From zero knowledge of hydronics 2 years ago, I still can't do anything useful, but have probably arrived at the dangerous level now. If you're writing "Hydronics for Dummies", I'm the one you're selling it to. I've put thermometers all over the place, and have temps racing around in my head. My house has 2 bb 571 ZVs and a Superstor 571 (no priority), all 3 driven by a single 007. The delta t from both bb zones is around 10 (I don't know what the original design delta was supposed to be). The wb is great and easily supplies 170-180* water. However, if I let temps in the house drop via setback, it takes what I feel is a bit too long to heat back up (i.e. 1 degree per 1/2-1 hour). The bb is clean, and I bled all of the zones. Once the target temp is reached, there's no problem keeping it there (but is more wood being used than necessary?). Yes, I can bump the aquastat up to produce higher temps in order to heat faster, but I'm trying to find out if there's something better. I've been wondering if the delta t should be closer to 20, but don't have a way to test this theory (would partially closing a shutoff prove anything?) So, I've been looking at what the Grundfos Alpha claims to be able to do via variable delta P, and am looking for feedback from folks having hands-on experience with it. At the very least ECM would save $ by running much more efficiently. And if autoadapt didn't work, there are also manual delta P settings to try. But, if autoadapt does work well, could it even optimize flow as the boiler water temp cycles up and down (on systems with no storage)? Maybe I'm off base on this, but it sounds like the Alpha can potentially optimize and improve most fixed-flow systems. This isn't urgent, and I don't have to make any changes - but would be willing to give it a try if there's good feedback on the Alpha.

 

[in hot water]

Do you have enough baseboard to cover the heat load? First you need to run a heatload calculation for your home. Then determine how many feet of baseboard it would take to distribute that much heat. Next measure how many feet of baseboard you have. Does it all add up?

Or too many baseboards oln one zone will drop the temperature to the last boards and reduce their output.

Actually the smaller the delta T through the baseboard the higher the output. It's the average temperature in the baseboard.

So 180 in 160 out = 340. Divided by 2= 170 average temperature.

180 in 170 out = 350. Divided by 2= 175 average across the baseboard. The higher the average temperature the greater the output. Slowing the flow does not allow more BTUs to jump off

This article explains the concept better, not sure if the graphics will download with it? www.pmmag.com/Articles/Column/de452c49e3fc7010VgnVCM100000f932a8c0____


Price sensitive contractors would sometimes boost the supply temperatures to 200 °F or more. This allowed them to use less footage of board and sometimes smaller pipe diameters. It was a cheap trick and usually lead to noisy, dusty operation, just to save a few bucks.

Get some stable data before you switch anything the load, and how much emitter you have.

hr

 

[willworkforwood]

Thanks HR for the detailed reply and all of the helpful info. I've been doing lots of energy improvements over the past couple of years, including homemade storm windows, and the house is getting tighter all the time. However, with some stuff still remaining, I'm sure there are not enough emitters for the current load. I was really asking the question generically - can the Alpha improve a given system, regardless of circumstances (looking for the silver bullet ;-) ). But your info about the higher delta t not being better makes sense now that I think about it further. I'm going to just finish the improvements that I know are needed, and then see where it's at (including the heat calcs that you suggested). But with the wb cooking, things are A-ok - I'll have to do a bit more splitting, but the oil gauge will stay right where it was in October :lol: . Thanks again for taking the time to offer your help on this.

 

[in hot water]

What the Alpha will do is adjust it's speed and gpm output based on how many zones are open. The pump senses the required flow and is always changing it's speed. It will save money on electrical cost as it is an ECM, rare earth magnet, high efficiency motor. Look for 40- 60% electrical savings. Compare the pump curves, I think it is a bit less than the Grundfos 15-58 or Taco 007, so it will actually move less load. But more efficiently than an "exact size" non ECM circulator.

hr