In-floor radiant heat system: Boiler issues

DPG · September 2014

My house is heated by an in-floor radiant heat system. The system has four zones, and is heated by a Teledyne Laars natural gas boiler (JVT100N CL). I have tracked down the manual for the boiler online, but it doesn't answer the questions I have. The house was built in 1994 and I'm pretty sure that the boiler is original, although a number of parts on the system have been replaced. There is polybutylene pipe carrying the water between the four zone valves and the return valves. Everything else is copper. Since it is summer I have the system completely turned off at this time (gas line closed, electrical kill switch off).

Since we moved in 5 years ago we have had numerous issues with the system (things like extremely slow response times to thermostat adjustment, patchy heat in certain zones, etc). I have had the system serviced on three occasions, but never to my complete satisfaction.

I have several different concerns about the system, so I am going to break it up into separate posts.

DPG · September 2014

Pressure issue

I see that the boiler is rated to a maximum pressure of 30 PSI. There is a pressure release valve on the boiler, rated for 30 PSI. The water line in has a pressure regulator set for 12-15 PSI. Yet, the pressure gauge on the boiler is showing around 52 PSI in the system right now.

Is this a major concern?

Is it just a function of the system being powered off? I did not look at the pressure before turning everything off.

Is the release valve not doing its job (it is very slowly dripping water)?

Is the pressure regulator not working?

Do I need to release this pressure in some other way?

DPG · September 2014

Flushing the system

The other day I began to flush the system. Corrosion of the Poly-B pipe has led to dirty water, which I want to remove from the system. The individual zones do not have spigots, so I instead connected a hose to the spigot on the return water side to drain the water. I flushed the system one zone at a time (with the other three closed) until all four were running clear. In all cases the water started extremely dirty. The dirtiest one took a lot longer to flush clean than the other three, but it is also the longest one.

Today I flushed the boiler itself through the shortest of the four zones, out the drain valve on the bottom of the boiler. This water started out as a thin, greasy, black sludge, but eventually ran clear. I then reflushed the zone that the boiler flushed through, but noticed it started out extremely dirty again. I expected that it could have picked up some dirt from flushing the boiler, but was surprised by how dirty it was. I then decided to check the other three zones, and they were all very dirty again, without having turned on the system.

Is this normal? Should I need to flush each zone multiple times for it to stay clean?

Rich_49 · September 2014

Where

are you located ? Do you know what kind of piping install you have ? Is the tubing down from the sub floor with an airgap , is the tubing strapped to the floor without any type of heat emission plate ? We need to know more . What kind of tubing is in the panel , PolyBute?

DPG · September 2014

More info

I'm located in BC, Canada. Since I'm not sure how to best respond to your questions I will post a few photos. The boiler is sitting on the concrete subfloor in a room with the hot water tank.

DPG · September 2014

Photos

Photo 1 shows the house water supply line > check valve > backflow preventer > release valve > expansion tank

Photo 2 shows out and in lines to boiler

Photo 3 shows zone valves on supply lines and return lines.

Snowmelt · September 2014

Clean water.

You have a cast iron boiler. You need to get fernex boiler cleaner with a magnet , you should replace the pressure reliefs valve.

Cast iron boilers will always carry dirty water unless cleaned and maintained.

DPG · September 2014

Pressure issue

I'm starting to wonder if the pressure gauge has crapped out. I have drained water from all three outlets (the two that can be seen in Photo 2, and the outlet at the bottom of the boiler) with no noticeable change on the gauge. I do know that the gauge is working for temperature as it began dropping after I turned the boiler off.

DPG · September 2014

More photos

Boiler and gauge

Zman · September 2014

Treating the symptoms.....

What you are experiencing is the damage done to a system that has non barrier tubing. The "gunk" in the water is the biproduct of the corrosion that is occurring. The Oxygen is reacting with ferrous metals and turning them into gunk.

The 2 choices you are facing are:

Repair the symptoms and get a bit more life out of the system. 20 years is pretty old for a teledyne.

Install a new high efficiency system with no ferrous parts. Boiler, circulators, exp tank should all be copper, bronze or stainless. And live comfortable ever after.

As a side note, radiant systems don't respond well to temp setbacks it is best to leave the t-stat alone.

Get a handle on the issues you are having with the pressure ASAP. Boilers really do blow up from time to time. Get an accurate pressure reading. if the T&P is weeping at 30# you likely have a bad expansion tank. You may also have a bad T&P.

If you have 54# for real, shut it down.

Carl

DPG · September 2014

Thanks

Thanks for the responses. At this point I would really like to try to get a couple more years out of this system, but know that replacing the boiler isn't far off. The expansion tank is new one year ago. I'm not sure whether it is iron or not.

Given that I don't trust the pressure reading on the gauge, is there an alternative way to check the pressure?

Also, when you're referring to a high efficiency boiler, are you talking about the super expensive 97%+ models?

DPG · September 2014

Pressure going up!

I just checked the gauge for the first time in 24hrs and I guess it is working because it has actually increased (up to 58 psi now). I am trying to do everything I can to prevent explosion but don't know what to do. The gas and electricity to the unit are off. I have drained water from all three release points on the system without reduction in power. The water supply line to the unit is off. What more can I do?

I have a friend who owns a plumbing company. I have contacted him to hopefully send someone but haven't heard back yet.

Zman · September 2014

Gauge

Your gauge is not working.

Replace the gauge or use a gauge that fits on a hose bib and check the real pressure. If you drained the system and the gas is turned off, you don't have pressure.

RobG · September 2014

What Carl said

Listen to what Carl said. Either remove all ferrous components from the system or flush it as you have you have been doing and use an oxygen inhibitor. Rhomar or Fernox products will do the job. Your pressure gauge is just as gunked up as the rest of the system, that is why you don't see the pressure drop when you let the water out of the system. Get a new gauge for your boiler and check the expansion tank and fill valve. It is always good to have a secondary gauge as well to spot check pressures.

You should also replace the weeping relief valve as well.

http://www.supplyhouse.com/Zurn-HGI-25-Hose-Bibb-Pressure-Gauge-with-Maximum-Pressure-Indicator?gclid=Cj0KEQjw7b-gBRC45uLY_avSrdgBEiQAD3OlxwpvrgZPlgCd4DBu06hrSinShDvEv129gybjmTke5iwaAjSL8P8HAQ

Rob

DPG · September 2014

Faulty pressure gauge confirmed

Thanks guys. I got a hose bib gauge as per Zman and RobG's suggestions and the pressure is reading right where it is supposed to be (a little under 15psi) on all three hose bibs on the system. I also picked up a new tridicator gauge to replace the faulty one on the boiler, but go the wrong length so will have to wait until I get a new one to confirm correct readings there.

Whew, at least it's not going to blow up.

In-floor radiant heat system: Boiler issues

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