Accused of incorrect piping!

flyrite14

Recently replaced a hot water boiler in an apartment building with a typical supply out/ return in, single pump configuration. Owner required that it be replaced with a copperfin tube boiler. We in turn installed the boiler piped in the primary/secondary configuration. Boiler works great and heats building. They tell us before we replaced the boiler they were able to replace zone valves in individual apartments by only shutting off one ball valve on the supply side of the zone valve. Not sure how this is possible without a valve or check on the return side. Ever heard of such a thing?

Zman

They may have been able to make quick change with the system pressured down and the valve closed. Kind of like when you hold your finger over the end of a straw.

I guess when you repiped you may have inadvertently made that "technique" stop working. I don't think from your description that you have incorrectly piped something or violated any industry standards.

delta T

Was there an integral check valve in the old pump? The only way I could see it would be if it were piped something like this:
Return pipe>pump towards boiler (with check)>boiler>Supply pipe with Expansion tank/fill valve>apartment supplies>shutoffs on the supply side in each apartment>zone valve>back to the return.

When you shut off the supply to the individual units, the check keeps the fill valve from back pressuring through individual zones. Draining water will however depressurize the entire return side.

It is certainly possible what he says is true, does not mean it is correct....

delta T

@Zman I could see that, certainly on the top floor. Agreed, does not sound like there is any error in the installation though. @flyrite14 do you have an installation manual with a piping diagram you could show the building owner to convince him that it is piped correctly?

flyrite14

They say the z-valves were replaced while system was in operation. The existing pump remained on the supply side "pumping away". Don't recall a check valve on the system return. Still don't see how it could depressurize the return unless it is not piped as a continous loop. Seems to me as a pressurized system it would still flow out the return as the path of least resistance. Hard to say not knowing how the system was piped. Showed them manufacture recommended diagrams as well as the "Heating Help" explanation of primary/secondary piping. They are also getting input from an onsite plumber they use who can't seem to grasp the primary/secondary configuration. It's funny how some people suddenly think they know more than you about something they've never done before! I'll get the rep out, maybe they'll believe him.

hot_rod

I'd question why they are changing the entire valve not just the actuator? Usually the motor is the failure point?

Unless they are upgrading to Caleffi

flyrite14

White Rodgers!

hot_rod

Oh!

Have them demonstrate how they replace valves without isolating both sides. Maybe we all learn something.

That being said I did a video showing a valve replacement with water flowing. I used the Caleffi PressCon valve and fittings.

Sawed the old valve out with a cordless Hackzall, pressed the tailpieces in and tightened the nuts, less than 3 minutes.

GW

Be nice if you had a pic of the previous system, they could explain what exactly they did for this procedure. Whole thing seems fishy

Ironman

Maybe if the pump was on the return (which is wrong) and the static fill pressure was low, the upper floors may have had little or no pressure when the pump was on. This can happen very easily when you incorrectly pump towards the PONPC instead of pumping away.

EBEBRATT-Ed

What @Ironman said is the only possibility I could see

j a_2

I think they are pulling your chain....It's amazing the stories some homeowners come up with...They think the way they are used to is the way it should be..Not