Need to replace check valve in Aquatherm piping; contractor wants to use copper

janwalker47

This property has a complicated heating system using Aquatherm piping technology. (Gas-fired condensing boiler, five zones, hybrid hydronic). It is extra complicated because of a initial poor design (2004) followed by a subsequent poorly conceived replacement of the boiler and controls (2017) by [a now defunct company].

During recent [heating contractor] visits, we have identified some failing components, in particular, an inline check valve on the zone for an upper floor. This is embedded in a stretch of the Aquatherm piping.

[Contractor] quotes approx $ to replace the check valve but they do not have the tools or training to work with Aquatherm. They propose cutting out the run of PP-R with the check valve and replacing it with copper. I'm not competent to know whether this is appropriate. Are the materials compatible? But hmmm, we're talking about soldering copper really close to heat-sensitive plastic piping?

Can someone tell me whether using copper to replace a segment of PP-R is benign? or likely to cause more problems down the road?

I have had trouble finding a residential heating contractor who works with Aquatherm piping (metro Boston area). So it would easier to just stick some copper in there unless there are issues beyond aethestics, truth/beauty, or whatever.

Can you please advise?
Thank you-
Jan

Sol_Brother

There is a possibility of problems from erosion of the copper in a situation with high velocity or aggressive water. It seems the copper ions then have bad effects on the PP-R. The Aquatherm website describes this at https://aquatherm.com/literature/intermixing-copper-tube-and-aquatherm
I found another polypropylene company's reference to it as: "Super-smooth PP-R pipes have a higher flow velocity than copper pipes. In mixed-material plumbing systems that combine copper with PP-R piping materials, it is critically important to limit flow velocities through each copper component to ensure that flow-accelerated corrosion of these copper components will not occur. The maximum flow velocities for the specific water temperature and water chemistry of the system (as published by the Copper Development Association) must be adhered to."
Since my experience is that check valves are a very common failure item (although this is mostly on domestic water with chloramines, not a hydronic system) I would encourage you to include a union and use a threaded check valve for the repair.

janwalker47

Being just the homeowner, I doubt that asking the contractor to "include a union and use a threaded check valve for the repair" would be met with anything other than bewilderment or an icy stare. LOL.

But it sounds as if some caution is needed before making this repair, if I read the stuff about water chemistry correctly.

hot_rod

How will they transition to the Aquatherm? Or is there a threaded connection to adapt in?

I think the compatibility issue with copper and PP-R was only on DHW piping, high temperature, high velocity, and high chlorine content. I think a hydronic system would not be an issue? Maybe call Aquatherm or the local rep.
Curious what the check is being used for, and why it would need service or replacement?

Caleffi, for one, makes union type, servicable hydronic checks

janwalker47

The check valve is for a Grundfos circulator that otherwise would send hot water backwards up a zone that isn't calling for heat. Having the valve there has worked for several years to keep the temp within 1 degree of setpoint. Recently (February cold snap), with the thermostat not calling for heat, that zone is from 2 to 8 degrees over setpoint and the return pipe is hot. Diagnosis: failed check valve.

Servicing the valve was not mentioned as an option. Is that likely to be possible I wonder. It is a straight brass-looking inline thing, same diameter as the piping.

They are talking about cutting at where the zone comes down from the 2nd floor and taking it all the way to ? I guess the pump itself? I gather they are not transitioning to the Aquatherm since they don't have tools, just replacing that whole run.

This is an expensive guessing game.

EdTheHeaterMan

Can you provide a photograph of the failed part? If the check valve is an item provided by Aquatherm, that repair would make sense. If the check valve is made by "other than" Aquatherm, then it should be serviceable. If it is near the circulator, with flange connections, then the replacement part may be available at a much lower cost than 2K. (Caution we do not discuss price here but I believe your vague approximation of 2K may be acceptable)

Pictures of the circulator and the check valve location will help.

Yours Truly,
Mr.Ed

janwalker47

Shoot. I had a comment typed in and lost it. Here's a very low res screen shot:

This seems to be the kind of thing I just saw on YouTube where you merely unscrew those big nuts and put in new internals to the valve. Is that possible?

janwalker47

I apologize for not having good photos but, not being at the property, can't get better ones at the moment.

The circulators are at the left with the red bodies. The pipe goes up and takes a turn over to the right. The one that failed is actually behind the visible one. It would sure be nicer if this were repairable.

Many thanks to you all for chiming in. It is super helpful to get the right terminology; helps with finding things like YouTube product vids.

mattmia2

You certainly could cut the ~3 ft piece with the ell that goes to the check valve, screw a new check valve in to the threaded adapter that goes out to the rest of the system and replace from the pump flange to the check valve with copper. You could also replace it with just a piece of copper pipe with a threaded adapter on it and get the check valve that goes in the outlet of that circulator. You might need a new flange that is threaded or sweat, I can't quite tell if those flanges have a special fitting on them for the Aquatherm or if they are just threaded isolation flanges with an adapter to the Aquatherm.

EBEBRATT-Ed

@janwalker47

Call Metropolitan Pipe and Suppl in the Boston area (Cambridge maybe they moved a few years ago)

They sell Aquatherm and can surely find you a contractor with the right tools. I don't think copper is the right fix.

Aquatherm requires special tools. I used to be certified but no longer am

hot_rod

Why do they suspect a bad check valve? Those are typical spring checks, while oversized they should seal. If they are noisy it is because they are oversized.

You could install check valves right into those red circulator pumps, at least they would be properly sized.
Adapt to the Aqua where the old check is removed, copper back to pump, fairly straightforward repair..
Looks like a blend of copper and PP R already in the system.

EdTheHeaterMan

It appears that you have an easy repair. It will include a replacement check valve, a union, and some adaptors to copper pipe. After you have the copper soldered to the adaptors and the circulator flange in the correct configuration Away from the plastic pipe, you can assemble the replacement fittings by turning the pipe threaded fittings back into the Aquatherm piping adaptor. Then the final connection is made by a union connection.

It does involve draining the boiler pressure and an experienced mechanic can swap out that check valve on the fly. An inexperienced tech will need to put a bucket under the check valve to collect any spillage. The check valve direction will hold the water back from the system once the replacement valve is in place. The valve on the circulator inlet will hold back the water in the other direction. You could lose a gallon of water on the floor in the process. By closing all the other service valves in the system, after the pressure is released to 0 PSI in the system, the change out is easy. Messy but easy.


Since your existing system should not have any more corrosion than a steel, iron, or copper pipes system, the Aquatherm is overkill for your system. there will be no ill effects by using a small section of copper pipe here. as illustrated. The cast iron in the pumps and the brass in the check valve are not made of Aquatherm.

I realize that the illustration shows a repair to a valve that s not defective, but it was the easiest to illustrate.

I hope the original approx $2k quote was not for a repair as illustrated here. If so, you should get another price from someone who understands Hydronics and can get the most economical and properly sized check valve for your needs. Caleffi has what you need and it is available at Supply Houses everywhere. If you are at all handy you may be able to DYI. But if you are not confident in your ability to solder copper pipes then call a pro.

Hope this helps to understand your situation

Yours truly,
Mr.Ed

janwalker47

Thank you very much for your detailed and thoughtful posts. I think, with this information to work from, I will look for another contractor for this job. (I believe those Grundfos Alpha II circulators have internal check valves but they are not up to the job for whatever reason, which is why there are external check valves on those zones. One of which has stopped operating correctly.)

hot_rod

Something fishy, the internal checks in the circulators should be plenty adequate for a properly piped and pumped system. Unless something is stuck in them. It is a very simple job with those isolation valves to remove the circulator and check or replace the Grundfos checks.

If in fact two checks on the circuit are not doing the job, replacing one will not solve the problem.

What exactly is the symptom causing them to condemn the check?

If it is an over-heating condition it may need a check on the return pipe, in addition to the one in the circulator. A bigger pic or a sketch of the piping may help us troubleshot virtually.

EdTheHeaterMan

I see where Bob is going here, I did not think of this because I believed that the problem just started and was not ongoing from the inception. Here is a section from my Go-To book on the subject.


It is from this book: http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf

The info starts on page 9. It calls the check valves "Flow Control Valves" from days gone by.

Today we refer to this phenomenon as "Ghost Flow." If the problem has just started recently then you may not have Ghost Flow, and the check valve may have failed. If the problem has been ongoing from inception, then replacing a flow valve or check valve will not resolve your problem. Good Call @hot_rod.

Mr.Ed

janwalker47

Here's the situation. The problem with overheating has been there since inception. Adding that check valve stopped the overheating. The overheating has very recently resumed. Perhaps I need to resume searching for a hvac PE who can advise on balancing the system. In the meantime, I need to somehow keep that zone from attempting to operate. Does just turning off the circulator do that? or will there still be heat flowing? [If you are a licensed hvac PE in the Boston area please message me directly.]

mattmia2

What are those circulators set to? Maybe one or more is set so high it is producing enough pressure to blow past the flow check in another zone.

Do you know if the circulators actually have a flow check installed in the circulator itself? You can order it with or without one and you can remove it when you install the circulator, so do you know if they are actually in place?

janwalker47

Hey I'm just the property owner and the original installer is defunct. Some old emails show that three years ago, the internal check valves failed in all of the Grundfos pumps. [Hmm, that's odd.] At the time, the guy said "we are going to put in external spring checks in all the zone some no long have cross tempering".

janwalker47

Aquatherm threaded adapter fitting from their design guide:

That looks like what is in my picture. What tools would you need to undo these adapters and replace the check valve?

hot_rod

You would remove the check and connect the copper to that adapter with a female adapter. Not pretty, but functional

EdTheHeaterMan

Looks like you would use adjustable plyers or pipe wrench on the green part of the fitting and a pipe wrench on the check valve to loosen the check valve from the adaptor. I would try it on the section of pipe you are replacing first. (left side in the illustration) If there is a problem removing the brass valve from the brass section of the adaptor and you find that you have crushed the adaptor and created a leak, then you can stop there, leave the defective valve on the other adaptor and replace the pipe from the valve to the circulator flange.



That replacement pipe can be copper and you can add a "Flow Check" that is designed for heating systems. They are less likely to fail.

If the valve removes easily, then you can try the right side adaptor with more confidence. Removing is better than abandoning. But you go to do what you got to do!

Hole this answers your query

Respectfully Submitted,
Mr.Ed

janwalker47

Hmm. I guess I have two questions.
1. If you can remove the check valve with wrench and pliers, why is there any reason to remove the pipe?
2. I don't understand the comment about a flow check that is designed for heating systems. What is the one shown in the picture designed for?