radiant floor heat

LsFarm wrote:I've found that if the circulator pumps are run every month, that the cast iron pumps work fine. I've never owned a brass circulator pump. I've had only one pump stick from corrosion, and it sat in pure water for almost a year. I took the motor/impeller off [4 screws] and wire-brushed the housing where it had grown some rust that touched the impeller, and is still running 3 years later.

I'm not a fan of spending 3x the money on bronze pumps when a cast iron pump will work in most cases. However there are exceptions. Yanche has really acidic water and his water system eats parts every few years.

Greg L

Granted that bronze pumps are more expensive. However cast iron pumps do corrode over time if there is oxygen in the system. I learned the hard way about cast iron pumps in a loop with oxygen. The pumps never seized but when I disassembled the system there were large chunks of corrosion product nearly totally blocking flow. If you have oxygen in the system you also need to use an expansion tank rated for domestic hot water because the less expensive units designed for boilers will corrode and spring a leak within a few years in addition to dumping corrosion products into the system while they are gradually being eaten away.

LsFarm wrote:Hi Ian, I don't think so either, but don't want to have some wierd microbe likes ethylene glycol to start growing in my hot water floor piping.

Do the rust inhibitors 'wear out' in antifreeze??

I know that some microbes don't mind high temps. Most start dying at over 125*, but with the wastewater, I have learned there are some that like it hot!

I think glycol starts to break down ovr 230-240*, not sure how that affects the protection properties.

If you want to remove the glycol from the water, you can do that with an Ultrafilter, the pore size is about 140,000 MWCO. Then you can dispose of it properly.

Hi Bob, well maybe I'm blessed with good water in my last three houses and the three or four I've been involved in installing and maintaining hot water heat systems..

Currently I have, eight pumps running, most are Taco 007 or clones, like a B&G NRF22, Grundfoss 15-58. I have a fairly high capacity Grundfoss 26-96 on the AA boiler.

All of these pumps are cast iron, and all the pumps in the past are cast iron. I've run at least half of them on oxygen rich or at least open systems. Other than the one I mention above, and it was neglected and was easlily repaired and put back in service...I've had only one failure, and it wasn't rust related.

I'm just tight with my $$ for a lot of things... [and a spending fool for others ] But I'd rather spend $45 [eBay, or $78 retail at my local store] for a Taco 007, and have it last 'only' 4-6 years and replace it than spend $190 for a Bronze pump and have it last 7-10 years. Just me.

I have had one pump fail, It was installed in this house's baseboard system when I bought it. It was a noisy pump for over 7 years, had a vibration. I had a spare on hand. When I finally died, I found that a glob of solder had wedged in the impeller and thrown it out of balance, and caused the bearings to eventually go bad. It was a two speed Armstrong pump in the s-30 capacity range. I can't remember the actual number on the pump.

Spend your $$ as you wish, I'm just saying that it is not a buy today,and fail next year proposition if you use a cast iron pump in an open system. They will last a long time unless the water is very corrosive, like Yanche's'

Greg L

Greg,

I don't think we disagree about the underlying facts. You reported corrosion in a cast iron pump--I characterized it as happening over time. What I was trying to add was a couple of points. First in my experience corrosion products can build up and block flow without causing a pump to seize. Second, expansion tanks are also subject to corrosion.

My experience and my post were consistent with your point that it takes years for the corrosion to cause failures.

I perhaps am willing to spend more in initial cost, for a bronze pump for example, to avoid a failure several years down the road. Failures always seem to happen at really inopportune times. I have Taco 007pumps that have been running 15 years. My understanding is that they should last considerably longer operating in benign conditions. Even the pumps I disassembled and found the blockage in were cleaned up and are still running. I have since corrected the underlying oxygen problem and hope that things will operate without problems for many years to come.

Wood'nCoal wrote:I suppose the fluid from the system could be filtered and the rust inhibitors replenished, much the same way as with auto antifreeze today. Or you can just do it the old way, flush it out and let the ground absorb it, then add new antifreeze (remember in the fall, all the "do it yourselfers" would have their cars backed into the driveway flushing the cooling systems out with the garden hose?).

http://en.wikipedia.org/wiki/Ethylene_glycol

Just a note to indicate that I wasn't suggesting that we all flush our antifreeze out onto the ground, or down the storm drain if you live where such drains exist, just pointing out something that was common practice in the past, I'm sure some people still do it.

i would never dump the antifreeze in the ground......anybody know what to do with it? i must have 75 gallons of used antifreeze

Check with the town where you live. Most municipalities can tell you what to do with it. Where I live the county has hazardous waste collection days at the MUA where you can take antifreeze, solvents, oil-based paint, etc. for collection.

i've been sending my buddy from new jersey home with a couple jugs of used antifreeze when he visits......they pick it up where he lives.....all i get around here is dump it out, ground is already polluted