exploded manifold

jfrancis

So a few days ago, my wife turned of the main shut off valve for the house in order to clean a sediment filter. After the job, she turned back on the main (very quickly she said) and it almost immediately cracked the supply HeatLink manifold of the hydronic system. She immediately turned of the water. When I got home, I replaced the broken section of the manifold (the heatlink manifold come in sections that are screwed together) and turned the main back on. Everything looked good - no leaks - and I left for 10 mins. When I went back down for one last check, I noticed the pressure was at 80 psi and climbing fast. Before I knew another piece of the return manifold cracked and water was spraying out like a fire hose. I should add I have a HeatLink system with 8 zones, actuators and bypass valve between supply and return. I am running this system off the same gas water heater as my domestic.
1) why is the PRV not going on the water heater?
2) If I shut off the supply manifold and turn everything on, my pressure still climbs
3) Expansion tank?
4) What is the relationship between this happening and the main getting turned on and off - trying to blame the wife.
Thanks, jon

SENWiEco

Water tank heater Temp and Pressure relief valves are typically set to go off at 150 PSI or 210F, so 80 is still well below this pressure.

There is a chance that turning off the main dislodge debris that is now stuck in the main PRV of the house. The odds are very high if the main shutoff was a gate valve instead of a ball valve and could mean the washer has degraded and started to fall apart.

But not sure how this pressure would get to the hydronic heating side of the system unless you are running the hydronic heating system at house pressure ??

Which is your system the closest to on the below diagrams

Gordy

Is there one of these, or similar on the hydronic side?

jfrancis

My system is quite different from the 3 diagrams.

jfrancis

There are 4 pipes coming off the water heater.
1) Cold intake which also feeds make up loop and mixes with hot
2) Domestic hot
3) 2 pipes for hydronic loop

I do have a regulator at the house main (not sure but think its set to 60 psi) and one on the make up loop 12-15 psi (shown in the pic)

jfrancis

jfrancis

To test to see if the main regulator is gone, could I hook up a pressure gauge to the hose bib above the expansion tank and turn off the valve above the hose bib T? That should be directly running from the main (except it runs through the 12psi regulator as well).

Zman

The regulator on the house should be keeping the pressure under 60#. The backflow/regulator device should be limiting the heating side to 12-15#. Your piping is peculiar, unless there is a heat exchanger somewhere out of the picture, you likely have an poorly piped open system.
Can you sketch out the piping?

Dan Foley

Looks like an early Combi- Cor which had an internal heat exchanger. Most likely the heat exchanger has failed allowing house pressure to the radiant manifold.

jfrancis

here's my best attempt. let me know if you need more detail.

hot_rod

If it is a CombiCor and the HX fails it will see line water pressure. Does the tank have a DHW expansion tank? if not pressure could go beyond what that manifold is rated for when it heats.

SENWiEco

What is the model of the water heater. What they are getting at above is there should be a coil inside of the water heater that separates the hot water you send to your taps from the hot water sent through the hydronic heating system. If the hydronic heating system is at 80 PSI you probably have multiple problems.

1) The main house regulator has failed or is not correctly adjusted. This is a for sure problem. Should maintain between 40-60 psig depending on model.

2) One of the two things have also happened on the heating side.
a) The make-up water regulator has failed allowing house pressure to enter the system.
b) the coil inside the hot water tank (which is a heat exchanger) has failed allowing the house 'tap' water to enter the hydronic circuit.

If the heat exchanger coil has failed, then you could also have contaminated water entering your 'tap' water. So make sure you do not consume until problem is fixed and the tank is flushed.

In my previous role as a home inspector, I found several regulators that failed once the main was turned off and then back on again. Usually because a piece of washer got stuck inside.

Good luck

jfrancis

If the heat exchanger in the tank failed wouldn't the regulator in the make up loop catch the increase?
Thanks for your help everyone!!

SENWiEco

No it would not. The water in the domestic part of the tank is obviously at 80 psi because the main regulator has failed. If the problem is with a failed coil heat exchanger inside the tank, then because the water on the outside of the coil is at 80 PSI, it is flowing through the holes in the heat exchanger pipe until the pressure equalizes. To test if it is the heat exchanger instead of the make up regulator, you would need to somehow turn off the make up water circuit (I do not see a valve but may be hidden), then drain down the pressure (turn off main and bleed it out of the hydronic loop), turn main back on and see if pressure rises again. If it does, the hot water tank is done and needs to be replaced.

SENWiEco

To further help clarify your question - the make up regulator is on the cold side of the hydronic circuit. But that coil is also connected to the hot side, so the flow and pressure are coming into the hydronic circuit from that direction bypassing the make-up regulator (again if it is the coil and not make up regulator)

jfrancis

If I turn on the main, then turn off the valve that feeds the make up loop - the pressure slowly rises - i let it get up to 30psi. If I keep that valve closed and close the valve at the end of the make up loop - the pressure goes shockingly fast. Not sure if this help but I couldn't believe how quickly the pressure went up when I closed both ends of the make up loop.

I will try the test recommended above for the heat exchanger.

To test the main regulator to the house, could I just try to turn it way down (i think it goes down to 25psi) and see what pressure is like coming out of the taps?

jfrancis

Here's the specs for the tank.

jfrancis

SENWiEco said:

No it would not. The water in the domestic part of the tank is obviously at 80 psi because the main regulator has failed. If the problem is with a failed coil heat exchanger inside the tank, then because the water on the outside of the coil is at 80 PSI, it is flowing through the holes in the heat exchanger pipe until the pressure equalizes. To test if it is the heat exchanger instead of the make up regulator, you would need to somehow turn off the make up water circuit (I do not see a valve but may be hidden), then drain down the pressure (turn off main and bleed it out of the hydronic loop), turn main back on and see if pressure rises again. If it does, the hot water tank is done and needs to be replaced.

So I turned off the Make up loop (blue valve in the photo) - dropped the pressure down to zero using the drain above the expansion tank, turned back on the Main and pressure seems to be staying at zero.
I have the supply manifold capped so no water is running through the zones (because the return is still broken). No sure if this plays into it.
Also when I turned the main on, I did get a steady stream of warm water coming out of the return mainfold where it is broken. I shut off the return to stop the water from running out.
So HX is good?

jfrancis

Spoke too soon. The pressure is going up - up to 40psi now.

SENWiEco

If the pressure goes up in the hydronic loop even with the make-up water shut off, you have a cracked heat exchanger coil.

SENWiEco

*** Except, based on the model number and this document

https://s3.amazonaws.com/bradfordwhitecorp/wp-content/uploads/residential_combination_combicor_atmospheric_vent_defender_non_defender_m2_c_discontinued_partslist_42502c.pdf

This is not an indirect tank with a built-in heat exchanger from what I can see. At least the diagrams and description do not talk about a heat exchanger???

SENWiEco

here is a better manual - yes there is a heat exchanger coil. So yours is toast - sorry!

https://s3.amazonaws.com/bradfordwhitecorp/wp-content/uploads/residential_combination_combicor_atmospheric_vent_defender_non_defender_m2_c_discontinued_specsheet_551b.pdf

jfrancis

Thank you so much for finding that manual. I was on the phone with Bradford White for a long time today and they couldn't confirm if it had the HX. Thanks everyone for help!!! You guys were way more helpful than anyone I called today! Looks like a blown regulator on the main, followed by a blown Heat exchanger (tank was form 1997 and probably close to going), followed by a blown manifold. I'm going to replace the main regulator tonight and then shut off the supply and return on the hydronic system (have to do both because of the leak). I'm thinking if I do that, I can run the tank and get some domestic hot water to the house - Which would be nice ( -25 Celsius tonight) . I guess I should drain the tank to get rid of all the hydronic loop water in the domestic? Probably only a small amount - should I worry about this?
Whats next? Keep the same system or go with separate boiler and water heater? I think I have lots of homework.
Thanks again.

SENWiEco

As I am not a pro - I will let others give you advise on what system to replace with. Good Luck

SuperTech

I would absolutely go with a boiler and an indirect tank for your home. A gas fired condensing boiler works extremely efficiently for low temperature applications such as radiant heating. Using a tank style water heater for space heating is asking for trouble in my opinion, even if it was designed for it. A boiler is a safer and more reliable option.

You want to avoid cross contamination of domestic water and space heating water at all times.

jfrancis

Hey Everyone, So I installed shut offs on both sides of the hydronic loop near the tank and drained the tank several times. My hope is to run the domestic until I figure what sort of new radiant set up I will be going with. Do I still need the expansion tank in the domestic loop? I'm assuming it was only installed for the hydronic loop. The reason I ask, is that I installed the shut off before the expansion tank, cutting it out of the system. I basically capped both radiant lines. Should I worry about expansion?

hot_rod

Are you on public water or your own well? Most public water providers have or are installing back flow preventers on all water supply lines. Or if you have your own back flow or a PRV with a check valve?

If you have one, I'd install it. All the recent plumbing codes require some sort of pressure protection device, thermal expansion tank or relief valve of some sort.

jfrancis

There is only a PRV on the water heater. No check valves expect for the backflow valve on the make up radiant line (which I have shut off from the system right now). We are on gravity feed water from a nearby creek and don't have a back flow valve on the main line.

mattmia2

Didn't you say you have a pressure reducing valve at the supply to the house? Those normally do not allow reverse flow so you will need an expansion tank on the DHW system if that is the case.

SENWiEco

This is often not the case. Many PRV's have an auto release. Here is Watts write up

The built-in thermal expansion bypass, another Watts first, operates on the principle of a check valve in reverse. Normally, the check is held closed by the street main pressure, preventing any flow of water through it into the system. However, when thermal expansion pressure increases to just 1 lb. to 2 lbs. higher than the main pressure, the check valve opens passing the expanding water back into the supply main at the rate it is expanded. Thus, the expanding water is dissipated (as in an open system) and the relief valve is not affected

mattmia2

That means that you won't get the pressure reduction function, it will for obvious reasons only be able to reduce the pressure to the main pressure, but it won't increase the pressure until some part of the system gives (hopefully the relief valve).

SENWiEco

True, but main pressure should still be below the relief valve pressure on HWT unless your municipal pressure is Really high. In this case it is gravity from a stream, so the 80 PSI the OP states, is probably the main pressure max.

jfrancis

Yes, I did install a Watts lf25AUB and left it at 50psi. Sounds like it would backflow before the Valve on the Water heater goes.

Jamie Hall

jfrancis said:

There is only a PRV on the water heater. No check valves expect for the backflow valve on the make up radiant line (which I have shut off from the system right now). We are on gravity feed water from a nearby creek and don't have a back flow valve on the main line.

In which case you don't need an expansion tank on the domestic hot water.

jfrancis

looking at a Rinnai M060CN. Thoughts?

mattmia2

I like my HTP UFT.

HTP Pioneer can solve a number of problems as well.