Long story, but indirect tank probably needs to be replaced. Not sure what to get...

thomase00 · July 30

I have a Megastor 40 gallon indirect water heater that was installed 14 (or maybe 12) years ago. 7.5 years ago, I had my boiler replaced with a EK Resolute 90+ system, also having the new system moved across the basement, and the Megastor with it. A few months ago, I got rid of my oil tank and had my EK Resolute 90+ switched from an oil to propane burner.

That brings us to the present. I'm in the middle of a major remodel of my home. The GC's plumbing subcontractor is not familiar with EK systems (but I don't think this is relevant). Since we are re-routing forced hot water baseboards, he needed to drain the system, cap off the old baseboard supplies, and then re-fill the boiler. Coincidentally, there has also been water main work being done in town that has led to frequent brown water (i.e. sediment) from the city. A day or 2 after the system was drained a refilled, I noticed water dripping from the boiler's pressure release valve. I ALSO started to notice occasionally creaking sounds coming from the indirect tank. The plumber identified that the boiler was over-pressurized at 40psi, so he let some water out, which stopped the leak temporarily. However, after a day, the pressure had climbed back up and the pressure relief valve was leaking again. I thought maybe the problem was that the sediment in the water had fouled the watts automatic fill valve for the boiler (which is supposed to keep the boiler pressure at 15psi), so I lowered the pressure back to 15psi, and then shut off the fill to the boiler entirely, BUT the pressure still climbed up to 25psi after a little while.

At this point, I'm worried that the boiler system water is getting pressurized through a leak in the indirect's coil heat exchanger, so I ran the same experiment, this time shutting off the supply and return between the boiler and the indirect. Now the boiler pressure gauge is staying at 15psi. I talked to one of the tech's from the company that services my heating system, and he agrees that there is likely to be a pinhole leak somewhere in the heat exchanger.

So it sounds like I'm going to have to replace my indirect, and I don't think I can reasonably blame the GC or his sub for any of this, given that draining and re-filling the system is a routine thing and the hot water tank was 12-14 years old already.

Along with any other thoughts and comments about the situation that people might be willing to offer, I'm wondering whether I should replace the hot water tank with another "generic" indirect tank, OR if I should replace it with the EK System 2000 branded tank that uses an external heat exchanger. I'll find out more tomorrow, but I suspect I'll have to wait longer to get the EK tank if it needs to be shipped from NJ, vs. whatever regular indirect tanks are stocked locally (I'm in Massachusetts). I don't think the limited lifetime warranty on the Megastor applies anymore since the tank was moved from its original install location.

Also, can I continue to run my hot water heater for a few days while waiting for a new tank, or is it best to just shut off the supply and return between the boiler and the indirect and go without domestic hot water in the interim? I don't expect any water from the boiler will make it into the domestic water system given that the domestic system is pressurized to 60psi.

HVACNUT · July 30

The EK water heater is specifically designed to receive the retained heat at the end of any zones cycle. They were made for each other. If the plate heat exchanger is already there, its a no brainer.

thomase00 · July 30

I don't have the heat plate exchanger. When the EK Resolute 90+ was installed, I already had the existing Megastor indirect, and although the installer COULD have pushed the EK heater, he judged that it wasn't worth it so he just piped the Megastor like a regular indirect.

At the time, the Megastor wasn't all that old. I recall that he also reasoned that there was no point in replacing it given that it had a limited lifetime warranty, but neither he nor I was aware of the fine print which says the warranty is only valid in its original install location (I had it moved). Not clear if "original install location" means "in the same house" or LITERALLY in the EXACT same spot.

mattmia2 · July 30

i don't see why moving it would void the warranty as long as whatever ownership requirements are met. if it were me i'd keep the isolation valves closed unless i needed dhw and just open them and run the boiler while i had a big demand like bathing or clothes or possibly dish washing, that would give me time to get the tank i wanted or work out the warranty. you can lower the pressure to maybe more like 5 psig since that is all on the same level and that will give you more run time before the pressure creeps up as long as you're not running the heating. the tank should stay hot enough for handwashing and kitchen tasks without running the boiler more than once or twice a day.

if the warranty is still good and is a full warranty i'd just replace like for like.

check the chlorides in your water, stainless will corrode with high chlorides. it usually is in the water department report. the manual for the indirect will have a spec for max chlorides.

if you have to buy a new tank i'd probably go with the ek and the hx and the ek controls.

thomase00 · July 31

I had a water test done a few years ago that showed 93.66 ppm for chlorides.

Also, I Megastor warranty is only valid when registered within 90 days of the install and unless the installer did something, I don't think I did. Didn't know any better at the time as a new homeowner...

mattmia2 · July 31

you can always try

Doug_7 · July 31

I am very happy with my Triange Tube SMART 316 Series Indirect Fired Water Heater. Had it for 15 years and still going strong. Very simple and very efficient. Doug

EBEBRATT-Ed · July 31

@thomase00

Don't tell them it was moved its none of their business and go for the warranty. Do what @mattmia said in the meantime about running the boiler for DHW

hot_rod · July 31

Make sure it is not the boiler fill valve that is over pressurizing the system. Same symptom as an indirect leaking across.

thomase00 · July 31

I think its BOTH the boiler fill valve and the indirect. If I cut off the indirect loop and open the supply to the fill valve, system pressure goes too high (~25psi). On the other hand if I open the indirect loop and shut off the supply to the fill valve, the pressure ALSO goes up.

It may be that the fill value got fouled by the brown water and sediment coming from the street due to water main work nearby.

mattmia2 · July 31

is the pressure still high when it is cool?

Robertw · July 31

Good morning, @thomase00, I believe I spoke to you yesterday on the phone.

It sounds like we were only half right with the fill valve being damaged by the debris in the water line from all the water main repairs. When you described what the screen in your shower head was plugged with, I figured if they filled the system at roughly the same time frame the pressure reducing valve was going to be affected.

We sell a pre-piped water storage tank with the heat exchanger that will directly replace the unit you have, if you're interested. Feel free to DM me and i can go over the specs for you or have your installer or plumber call us for pricing. The pre-piped feature saves roughly an hour and half in labor.

Long story, but indirect tank probably needs to be replaced. Not sure what to get...

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