Cavitation in Colorado radiant floor system

flanger

Now that's an easy change and a good idea! I already have two bypass attachments that will work to test it (although not ball valves) and the hose (it's what is rigging the Expansion Tank connection in the picture). If I just set that up to bypass, then I can easily see if 1) that stops the cavitation and 2) still permits enough heat to be gained from the heat exchanger. I'm don't know fluids, but my concern would be that the flow would always choose the hose if Hx's cause a lot of resistance by design (or is that electronics I'm think of :) ). I will try this out and report back. Thank You.

flanger

Cavitation in Colorado radiant floor system

I have four zones operating with Taco 009 pumps. The system runs fine when 1, 2, or 3 zones are running, but when all 4 are on, the first zone pump(on the supply side) gets noisy and does not pump through the zone. Without intervention, it overheats. I have already replaced 2 bronze ($$$) pumps, motor and all. The system runs at 20lbs static pressure and supply side max temp is about 145*. Each zone pump decreases the pressure a bit when running, and when all 4 zones are on, the system pressure is down to about 5lbs. Replacing the expansion tanks has not helped, just cost money.

I can’t quite remember when this started, but I am thinking that when the heat exchanger was placed in between the boiler, the system lost the ability to supply all 4 zones without creating a vacuum. Each zone is 3/4" piping, feeding supply and return pipes which are 1.25”. However, the supply and return pipes are reduced to 1”, and then again to 3/4" as they run through the Hx. I’m thinking this is creating the supply side pressure problem when all 4 Taco pumps are on.

Before I invest in more contractors, I was considering 1) Reduce the Flo-Setters in each zone (old, corroded Taco Flo-setters are installed on each zone). Would this damage the pumps or system? Would the house stay warm? 2) Adding a “master” pump to the main loop to keep things moving. Would this cause more pressure problems? 3) Re-pipe the main loop to use a 1” Hx and never reduce to 3/4”? 4) Just live with it since the 25yo 3/8” EPDM tubing in concrete might be nearing the end of its useful life anyway.

In pictures, disregard the piping on Expansion tank. Contractor piped it to return side, so instead we re-attached via washer hose to supply side (thanks ME).

larry_36

> I have four zones operating with Taco 009 pumps.

> The system runs fine when 1, 2, or 3 zones are

> running, but when all 4 are on, the first zone

> pump(on the supply side) gets noisy and does not

> pump through the zone. Without intervention, it

> overheats. I have already replaced 2 bronze

> ($$$) pumps, motor and all. The system runs at

> 20lbs static pressure and supply side max temp is

> about 145*. Each zone pump decreases the

> pressure a bit when running, and when all 4 zones

> are on, the system pressure is down to about

> 5lbs. Replacing the expansion tanks has not

> helped, just cost money.

>

> I can’t quite

> remember when this started, but I am thinking

> that when the heat exchanger was placed in

> between the boiler, the system lost the ability

> to supply all 4 zones without creating a vacuum.

> Each zone is 3/4" piping, feeding supply and

> return pipes which are 1.25”. However, the

> supply and return pipes are reduced to 1”, and

> then again to 3/4" as they run through the Hx.

> I’m thinking this is creating the supply side

> pressure problem when all 4 Taco pumps are on.

> Before I invest in more contractors, I was

> considering 1) Reduce the Flo-Setters in each

> zone (old, corroded Taco Flo-setters are

> installed on each zone). Would this damage the

> pumps or system? Would the house stay warm? 2)

> Adding a “master” pump to the main loop to keep

> things moving. Would this cause more pressure

> problems? 3) Re-pipe the main loop to use a 1” Hx

> and never reduce to 3/4”? 4) Just live with it

> since the 25yo 3/8” EPDM tubing in concrete might

> be nearing the end of its useful life anyway.

> In pictures, disregard the piping on Expansion

> tank. Contractor piped it to return side, so

> instead we re-attached via washer hose to supply

> side (thanks ME).



looks like you have that exspansion tank hooked to the supply and return only way the the pump shows negative pressure is when you pump into the tank those are high head and high flo pumps do you need all that ?

larry_36

looks like you have that exspansion tank hooked to the supply and return only way the the pump shows negative pressure is when you pump into the tank those are high head and high flo pumps do you need all that ?

J.C.A._3

Nice camera....

P*$$ poor boiler piping!

Use the top of the main page and the Find A Pro box.

You think that moving the expansion tank costs too much? How much did the bronze pumps....(that are probably WAY oversized BTW) cost?

It looks and sounds like you're chasing your tail here.Get a pro to help you out of this pickle, and save your time and money for something like a good vacation.

Sorry to be so forward, but I just "calls em' like I sees em'" Chris

ALH_4

hx

Is there a possibility the EPDM tube has deteriorated inside and plugged the heat exchanger? It looks like you have valves to connect a transfer pump and backflush the heat exchanger in a white bucket of clean water.

flanger

Excellent idea! There has been so much corrosion, especially from when it wasn't seperated with a Hx, that might help. The last heating pro I had out suggested not back-flushing the zones because he was afraid of damaging the tubes or Solaroll manifold connections. But the Hx is totally safe. I will try that this weekend. No one seems concerned about the main loop reduction from 1.25" to .75", so that is helpful too.

In response to earlier replies - I think the pros have picked the 009 pumps because of the high friction head resulting from the old, thin EPDM. Bronze, of course, because no more o2 barrier. They cost about $300 when they burn up (cartridge only is about 1/2 that). I have had six radiant-floor pros work on the system over 10 years (about 15 visits) and some don't want to mess with it (usually afraid of age and type of tubing, buried in concrete). All of the plumbing in the picture was done by radiant floor specialists. They have kept it running, but the cavitation problem has not been solved. Since I have rigged up the Expansion tank to be running off the Supply side (valve shut-off from the Return side), it seems this will not help, but I will have it moved next time pipe work is done.

jp_2

what if?

you allowed only 3 pumps to run at a time?

flanger

That's what i'm doing a lot of right now. I set up the programmable thermostats to stagger in the evenings (days are not problem becuase whoever built the house did an excellent passive solar design). When it's really cold out, I shut off a lesser-used part of the house and just let it get really cold so the rest of the house can run without me worrying about it. I don't schedule vacations during the coldest months .

Weezbo

in a way this might be a help...

have you tried a bypass ahead of the heat exchanger with a size closer to the headder tubing,?

hear me out...instead of sending All the Flow by means of high head circs,how about go with the heat exchanger as a type of injection system and let them flow like crazy through the by pass and pick up the highest temps it can on the way by...the heat exchanger.... you might find that the solaroll likes lower water temps anyway.

instead of Forcing super high head through at an increasingly more expensive operation each winter, why not dial everything Down instead of up...?

the flow would be better for the circs and your not going to get anything More out of the heat exchanger however You just might decrease the expansion of the tubibg with lower temps ..the Btu distribution should also increase..i have to say the zones may stay on longer yet, the ciircs will either live longer Or you could make certain you need that size circ...we have some smart engineers here let some time roll by my thought and see if it makes sence to you...think about it...you got time. *~/:)

ok . i am going to Dress this up for you a bit. take some washing machine hoses and hook one up ahead of the spirovent and the other on the lowest purge on the return to the heat exchanger.. on the Stainless /Brass/ non O barrier side....instead of the water spinning through the heat exchanger exclusively ,the circs will mix cooler return water back into the wider stream of flow. albiet not much ,as the washing machine hose is like 3/8ths at best....if that "Seems to do something for it ...then pipe a 3/4 line from the 1 1/4 to the 1 1/4 with a globe or even a ballvalve....start out with the system doing what it is doing , then ,open the ballvalve...let it run for a half an hour or so... if the noise dies down and the rooms are staying warm..then you have cured some of the evil...you would probably not need more Bigger Higher head circs at all. it is more likely it will behave much better ...on lower flow possibly even less head than One circ can generate.

Weezbo

is it ok to ask you a couple questions?

sometimes when i am Really getting urinated off about things i dont respond well to questions:) thought i would share that consideration with you first:)


1. what is the current temp ,going ino the heat exchanger?on the boiler side?

2. is it on Go basically or does it have some "control stradgey that takes into account supply and return temps?

3. do you have some idea of the amount of space actually "heated by the heat exchanger,and the relative dimensions of the individual zones and the largest zone?

4. Does the boiler shut off and on as it trys to keep up?

5. do any of the zones ever get to an off condition?

flanger

sure thing...

[Deleted User]

Been there, seen that...

literally...

As I remember, changing the PONPC with garden hose made a world of difference. I'd suggest a complete replumbing of the system, flushing of the heat exchanger and general re-build and chemical induction.

Rhomar makes some cleaners that are compatible with the rubber hose, and if it does fail, it needed to be replaced any how...

Must suck having to plan your vacations around your heating system...

ME

Weezbo

Hello Mark. *~/:)

o.k.:) i am off to work you know what he is looking at and understand my questions... Thanks ...:)

flanger

sure thing...

sure thing...
1) During normal winter, 180-200. During cold snaps, 180-220. I change it when Kathy Sabine says it's going to be a cold week.
2,3, and 5) It is on GO. On a normal Colorado winter day, it starts from a completly cold start at about 6pm. Passive solar keeps the house toasty most days). Most zones are completly off from 11am to 6pm. I have considered an outside controller to get a jump, but it is lower on the priority list. The crown boiler fires up for about 3 min to get from 180 to 200/220. (There is very little piping on the boiler side). Then the Hx takes about 5-15 min to lower the boiler temp back to 180, depending on the radiant return temp.
3)This is a thought-provoking question. The Hx is supporting 2700sf. But the zones are 300sf, 300sf, 700sf, and the 1400sf upstairs. However, the 700sf zone is my least favorite. When it goes on, it drops the pressure much more than the others (like 5-8 lbs). What's different about it is that the copper tubing splits (somewhere) into two copper lines feeding two seperate manifolds. One is for the back bedrooms and the other is for the 150sf sun room. Perhaps two manifolds off one zone is a no-no. I can't say for sure, but I have a feeling that this is always the zone the causes the most trouble.

flanger

Hi Mark,

The washer hose trick raised my confidence. If you recall, the cavitation was happening almost every morning. Now it's only when all 4 zones are on. I'm starting to think maybe I can get another 20 years out of the EPDM and manifolds. If I keep the temp at 145 and pressure at 20lbs (when no zones are running), and can overcome this cavitation issue when all 4 zones are on, maybe the tubing will outlast me

My plan of action this spring will be to 1) run a few days of cleanout with the Rhomar cleaning solution (I still have plenty) 2) replace the fluids with Rhomar/glycol mix (I have none) 3) Make sure the tubes and manifold connections are still water-tight 4)Boiler flush and tune-up (it's been running perfectly for 7 years, but that's a long time, right? 5) offically move the exp tank to the supply side. Any other tricks that cause improvement based on all this feedback. I'll be calling AH Inc, for all this, of course.

hr

Is this Solar or RadiantRoll tube?

25 years old is a bit too early for any of the Heatway EPDM tube.

If it is black, dual tube, EPDM then it may be Solar Roll. Funky header and hose attachment, like the pic?

This tube is actually a 1/4" id. It does age and may split at the connections, especially if you try to remove them.

If you do try to salvage it I would disconnect and flush every loop with 50 PSI. Just flowing through the manifold may not open sludged loops.

I'd also pressure test every single loop, while they are off or you will have a constant fill system

Brass adapters to fit that tube can be found at welding supply shops. Also some automotive, although they are often plastic adapters these days.

The very early Heatway TwinTran prototypes actually used a swivel nut connection like seen on Oxy/actylene hose. Very handy for purging and troubleshooting. Fairly expensive fitting with a special crimp tool required.

hot rod

Sorry the attachment will not stick with a solar roll header. I'll try later

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

flanger

This IS Soralroll tube - when I moved in I was confused because I saw the name on a manifold, but don't have solar panels (ME confirmed it when he came out). I didn't realize it was 1/4"id. (but now I see that). Thanks for the tip on the brass adapters - I didn't think I would ever be able to replace those. I found a section of exposed tubing in a crawl space and it seems to be solid and not cracking, so I'll keep my fingers crossed.
Any other tips/experience/history with an old Solarroll design regarding heat, pressure, glyocl, etc?

This will be my last radiant floor system because I will not bring in the Jackhammer squad for all of my floors (although I would consider replacing with radiant ceiling if the tubing fails). I figure I have about 40 years left, so that will require that this tubing lasts a total of 65 years .

hr

I will say this about those early

SolarRoll systems... they provided a very nice even floor temperature, no striping what so ever. A `combo of the wide mat and the counterflow fluid direction.

The biggest issue was reduced flow due to the ferrous components disolving and plugging the tube.

IF in fact they all flow, and none split at the manifold, who knows? It could run 5, 10, 30 years or more.

Fluid quality or non ferrous components are the key I feel.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

flanger

Wow - nostalgic pictures

Thanks for the feedback and photos. It's ferrous-free and I'll be sure to keep the water healthy. If it ever fails, I'll be sure to post.