alaskagreen
New Member
Posts:10
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| 12 Mar 2010 07:10 PM |
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I am thinking of using grundfos Alpha pumps as Zone circulators for a multizone residential heating system with mostly hot water baseboard zones and one radiant zone. The alpha still is not designed for relay zone control, and I'm not sure what would happen to the Alpha's adaptive functioning if it's power were cutoff with a relay connected to the AC outlet supply the Alpha power. Has anyone heard of this being done with several Alphas as zone circs instead of using zone valves? The price of the Alpha is very close to the regular grundfos UP-series pumps, and no pump manufacturer has the perfect pump for all of my zones head loss/gpm requirements, which makes the Alphas look pretty attractive! Plus, I can read the gpm flow for each zone from each pump's display. |
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BadgerBoilerMN
Basic Member
Posts:468
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| 12 Mar 2010 07:17 PM |
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I think you are missing the point. The Alpha adjusts for flow, one pump multi-zone.
If you can buy Alphas the same as UPs please give me your source. The savings on a 3/4" baseboard system (very little head) is next to nil for residential application, but your thinking green. |
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MA
www.badgerboilerservice.com |
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alaskagreen
New Member
Posts:10
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| 12 Mar 2010 08:20 PM |
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Maybe I have an impractical idea.... But, ..... The Alpha is also suited as a zone circulator, and it's brains have advantages there too, is that incorrect? the mention zoning with alphas as an application on their website. so if the prices is nearly the same, why not use them?
The Alpha is only 10% more than a UP15-42BUC5 and only 5% more than a UP15-42BUC7. You can find these relative prices on the internet. I like the idea of the alpha's being able to display gpm flow.
I was planning to zone with properly sized circulators anyway, otherwise I would have to do some flow control valves due to variations among the zones. Another reason is that I get tired of zone valves going out and risking a zone freeze up here in Alaska. Every few years I have a zone valve go out, taco or honeywell, doesn't matter. There really aren't exact size circulators matched just right for each zone, a few would have excess flow, so I would have to add flow control valves. It looks like the Alphas would adapt to each zone. I only have two zones that would require me to set the alpha at a constant low speed mode, as the autoadapt curves handle all the rest of the zones requirements.
So, my question is about using alpha's as zone circs without zone valves and whether or not cutting power to the Alphas via relay adversely affects the alpha performance in this situation. they are supposed to be coming out with an alpha designed to wire direct to relays soon, but it isn't out yet. I have a call into Grundfos on this issue, but they haven't returned my message yet.
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alaskagreen
New Member
Posts:10
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| 12 Mar 2010 08:20 PM |
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Posted By alaskagreen on 12 Mar 2010 08:20 PM
Maybe I have an impractical idea.... But, ..... the Alpha is also suited as a zone circulator, and it's brains have advantages there too, is that incorrect? They mention zoning with alphas as an application on their website. so if the prices are nearly the same as quality grundfos UP series circs, why not use them in designs using zone circulators?
The Alpha is only 10% more than a UP15-42BUC5 and only 5% more than a UP15-42BUC7. You can find these relative prices on the internet. I like the idea of the alpha's being able to display gpm flow.
I was planning to zone with properly sized circulators anyway, otherwise I would have to do some flow control valves due to variations among the zones. Another reason is that I get tired of zone valves going out and risking a zone freeze up here in Alaska. Every few years I have a zone valve go out, taco or honeywell, doesn't matter. There really aren't exact size circulators matched just right for each zone, a few would have excess flow, so I would have to add flow control valves. It looks like the Alphas would adapt to each zone. I only have two zones that would require me to set the alpha at a constant low speed mode, as the autoadapt curves handle all the rest of the zones requirements.
So, my question is about using alpha's as zone circs without zone valves and whether or not cutting power to the Alphas via relay adversely affects the alpha performance in this situation. they are supposed to be coming out with an alpha designed to wire direct to relays soon, but it isn't out yet. I have a call into Grundfos on this issue, but they haven't returned my message yet.
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jonr
Advanced Member
Posts:911
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| 12 Mar 2010 11:12 PM |
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Perhaps creating some "leakage" around each valve would help prevent freezing in case a valve fails. I'd consider solid state relays if you decide to use relays - they are more reliable.
I don't know about the Alpha, but looks like it would pay for the cost difference in a year or two.
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alaskagreen
New Member
Posts:10
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| 12 Mar 2010 11:38 PM |
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Thanks, I was looking at the Taco SR50* exp series, but I don't think they are solild state. I found a Power IO box but is $1600, maybe solid state is too costly.... Who makes a less expensive solid state expandable controller switching relay box like the Taco series?
Anyone with thoughts on the question of an Alpha pump on a signle zone being powered off and on by relay from thermostat? Will it mess up the Alpha's ability to adapt? |
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BadgerBoilerMN
Basic Member
Posts:468
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| 13 Mar 2010 12:09 PM |
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There are vary few pumps small enough to be efficiently used for zoning residential applications. Your zone valve failure may be do to design water temperatures being too high. This will cycle any zone control more than is necessary shortening zone valve or pump life and increase pump operating cost.
There is no evidence that circulators are in any way more reliable than zone valves ( I have replace both in the 30+ year range).
Balancing is not difficult and probably unnecessary if you have BB fin and 3/4 copper you are likely over-pumped wiht one circulator.
The Alpha cost three times and much as a three speed UP in the lower 48.
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MA
www.badgerboilerservice.com |
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NRT.Rob
Advanced Member
Posts:958
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| 14 Mar 2010 10:07 AM |
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SOME zone valves aren't very good.
we have had *excellent* service records with TAC Erie zone valves though. as in, I've never seen one fail. We were zone by pump for quite awhile though because of the old wirsbo and sparco zone valves/actuators. these days things are different though.
by the way: the pumps you cite as comparisons to the alpha are bronze construction. they are very expensive pumps. the alpha that is close to price to those pumps is cast iron. If you need non-ferrous construction for some reason, the stainless steel alpha is *much* more expensive. If you don't need non-ferrous pumps, badger's comment on pricing is correct and regular 15-58's are about a third of the cost of the alpha.
I have dreamed of a zone by pump alpha system, all low speed (3 GPM/3Ft of Hd and max 8 watts of power... sweet). But not until the price comes down. a lot.
we run alphas on relays. You aren't asking the pump to adapt (that is only for multizone systmes), so its ability to do so is moot. you should simply pick the fixed speed you want it to operate at if you're going to do this, and if you can, pick low. But there would be no economics in this choice unless your cost for electricity is truly huge. |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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alaskagreen
New Member
Posts:10
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| 15 Mar 2010 01:27 PM |
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thanks everyone.
I didn't realize I was pricing bronze pumps. duh!
I decided to go with zone valves after all, and a Wilos Stratos ECO system pump.
I think that my zone valve failures were more likely due to excess pressure than high temps, I run the boiler at 178 max temp but the system pump is constant speed and there is no bypass valve in the system. It wasn't very well designed, but it's 20 yrs old. The longest zone has a head of 8.5 and the pump is a ups 15-42f.
I am having trouble picking from the many varieties of TAC erie zone valves, the VS series has 4 different 3/4" normally closed valves with different head loss and closing pressures. VS2323G14A020 seems like a good choice but I'm not sure. it has a head loss of 3.5' and closing pressure of 25 psi, or they have one with a head loss of 2.5 and closing pressure of 40 psi........ |
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BadgerBoilerMN
Basic Member
Posts:468
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| 15 Mar 2010 02:31 PM |
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Honeywell makes and sells more zone valves. Operating temperature has little to do with longevity or reliability. It is about the cycle life as I stated before.
I not sure how, but you came to the correct solution in any event. |
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MA
www.badgerboilerservice.com |
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NRT.Rob
Advanced Member
Posts:958
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| 15 Mar 2010 02:33 PM |
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I don't know about that. I suspect high pressure was a part of the old school failures too. but i'm just guessing. |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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BadgerBoilerMN
Basic Member
Posts:468
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| 15 Mar 2010 02:35 PM |
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Yes you are, but nice try. |
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MA
www.badgerboilerservice.com |
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alaskagreen
New Member
Posts:10
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| 15 Mar 2010 02:38 PM |
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Thanks Badger. The old boiler was oversized and non modulating so I'm pretty sure it was short cycling along with the zone valves.
NRT, I just edited my post with question about the TAC erie zone valves. They sure have alot of choices!
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NRT.Rob
Advanced Member
Posts:958
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| 15 Mar 2010 03:01 PM |
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lower head loss if possible, but make sure the head pressure setting of your bypass or max head requirements won't lift the valve open. |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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alaskagreen
New Member
Posts:10
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| 15 Mar 2010 09:00 PM |
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The specs on that Wilo Stratos ECO have it putting out 15.5gpm max at 0 head, and 11gpm at 7 feet of head. The Wilo curve shows it doing 15gpm at 2 feet head.
My longest zone loop has a head loss is 5.6 plus my primary loop head is 5.9 for a total head of 11.5,
my 7 zones supplied have a design requirement of 15 gpm,
The parallel zones will have a combined head loss that is much less than 7 being in parallel, actually less than 1 by my calculation plus add on the primary loop head of 5.9, so I get an estimated head of 7 that the system pump will see at design conditions with all zones open. It doesn't look like the Wilo is quite strong enough for my system...... Neither is the Grundfos Alpha, I know for sure.
It looks like I have to step up to the Grundfos Magna 25-60, the smallest 230 volt version of the Alpha. I don't see much else out there for intelligent ECM pumps that can handle 7 foot head and 15 gpm. I haven't got a price on the 25-60 yet...... but it's got to be crazy expensive being a commerical pump.
Maybe I could use two Alphas for a system pump?? I have to study up on dual pumping...
Thoughts? |
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NRT.Rob
Advanced Member
Posts:958
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| 15 Mar 2010 09:10 PM |
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at your flow requirements I would use two smaller system pumps instead of one bigger one. Probably cheaper up front, and in operating costs as well. more labor to install though, if that's a concern.
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-=Northeast Radiant Technology=-
NRTradiant.com |
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alaskagreen
New Member
Posts:10
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| 15 Mar 2010 09:40 PM |
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NRT
And I would need to break out essentially two system loops for that? Current design is per lochinvar KNB210 manual, boiler on a secondary loop, and the system pump on primary loop. I guess I could come of the boiler loop with two closely spaced Ts to a second system loop, just like my current primary loop is connected, and in effect have two primary loops, with half the zones on each one.. Is that whay you are thinking? then an alpha circ in each primary loop? sounds like some type of piping could work, some extra copper and install time, but saving hundreds of dollars by not buying the Magna. This would also give me some redundancy to the system in case one system pump fails, I would still have some heat. I'm not quite sure how to pipe that without the 2nd system loop getting return water from the first! How about hydraulic complications with this design, would there be some conflicts that might need resolution with check valves or something?
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