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.

thomase00 · August 5

I might just go for a regular indirect. In that case, I'm curious why my original Megastor does NOT have an anode rod like the newer Megastor II. The Superstor tanks are also stainless steel (although the heat exchanger is Cupronickel) but do NOT have an anode rod. Do I need to replace with a Megastor II in order to be even considered for warranty reinburstment? One contractor I talked to said that the manufacturer will take the old tank back and inspect it first to determine if I'm elligbile. Otherwise, based on the boiler and domestic inlet and outlet locations, it looks like the Megastor II requires less reworking of the piping compared to the Superstor.

Also, for all these years I have not had a potable water expansion tank on the cold water inlet of the indirect. Should I have one? I'm on city water with a pressure reducing valve bringing the pressure from 100psi down to 60psi in the house.

thomase00 · August 5

How do I tell if this is an open or closed system (see attached photos)?

The main shut off is on the left, in the middle is my water meter, and to the right of that is a Watts LF25AUB-Z3 1/2" pressure reducing valve. Up top out of frame is the irrigation meter etc. which I don't think is relevant.

Is it weird that the PRV says 1/2 when the pipes connected to the inlet and outlet appear to be 3/4"?

mattmia2 · August 5

because of the laws of physics, water can't flow from low pressure to higher pressure so you need a dhw expansion tank with a pressure reducing valve. perhaps this is why your tank failed.

thomase00 · August 5

So, even though there may not be an actual check valve, the higher pressure on the street side of the PRV effectively makes my system closed from the perspective of needing a DHW expansion tank?

bburd · August 5

Before backflow preventers were required on incoming water services, the expansion would just flow back into the water main. The PRV almost certainly contains a built-in backflow preventer which creates a closed system on the house side of the meter, so the expansion has no place to go—and it will cause large pressure variations that will stress the hot water tank. There is sometimes enough pressure to trip the safety valve, usually set at 150 psig.

This is why a small expansion tank is now needed at tank type water heaters.

thomase00 · August 5

Realized another potential problem with my current install. The indirect loop to and from the boiler is piped with 3/4", while both the Superstor and Megastor installation manuals call for 1".

GGross · August 5

https://forum.heatinghelp.com/discussion/comment/1861662#Comment_1861662

If you get enough flow to transfer the needed heat to the tank without exceeding recommended flow velocity in your supply and return piping that would be fine.

hot_rod · August 5

The 25 AUB is a bypass type PRV and will allow pressure back into the main. But a DHW expansion tank is always a good investment.

The valve pictured is for the entire home? It is not a boiler fill valve, wrong pressure range for a fill valve.

3/4 piping to the tank coil can be fine if the tank has performed adequately?

HVACNUT · August 5

I still can't believe an EK tank and HX isn't already on order. Warranty or not on the MS. The only way it makes sense to me is if the OP doesn't understand how the EK boiler and EK water heater work together. You will not get the benefits out of the boiler using a standard indirect over the EK water heater.

Roger · August 5

The best option is an EK tank with the plate heat exchanger (higher efficiency, faster recovery, takes advantage of thermal purge). It can be piped by adding the plate heat exchanger in the bypass (the fittings come installed on heat only systems so that is easy to mount), or install it on it's own zone. Please contact our customer service team at (908) 735-2066 if you need assistance or to connect us with your heating professional.

Thank you,

Roger

thomase00 · August 5

I understand the benefits but it's complicated since I already have a GC and his plumber in the house working on a large remodel and he proposed putting in another indirect. I've never run out of hot water with a regular indirect so it's really just a question of whether the efficiency gains are worth finding someone else to put in the EK tank. The original installer of my EK system is no longer in business. They were bought by another company whose new owner is anti-EK and all the EK-trained techs have left.

Roger · August 5

Please contact us or have your plumber contact us as we sell to heating professionals. Annual fuel savings (not just hot water savings) are often in the range of 5% to 10% as the plate heat exchanger and tank that stratifies to allow thermal purge year 'round vs the boiler finishing hot with and indirect tank with a coil.

Roger

thomase00 · August 5

The fuel savings amounts to a few hundred $ a year BEST case. The problem is that the plumber I have is trusted by my GC and has done great work so far on the remodel, but I don't want to jeopardize the relationship with the GC by insisting that his plumber do something different that what he has done 1000s of times before over the past 40 years. I'm sure he is capable of figuring it out, but I don't want to make the guy think that I THINK I know better than him. I already interrogated him about a lot of other stuff and got the feeling that both him and the GC did not appreciate it. My house is currently torn apart, so I'm not going to take the risk of the plumber or his GC walking off the job. The GC is in high demand in a wealthy town and I had to wait a LONG time for him to have availability.

Of course I'm not obligated to use the GC's plumber for this, but he's already doing so many other things, that it would be weird to have someone different to come in while he's working in the same house. I've already contacted EK have have a list of local dealers and techs directly from them who would be more familiar with putting in the EK tank, but the dealers have been slow in getting back to me. In fact, one of the references given to me by EK was a heating tech who is VERY knowledgeable about EK equipment (but is not a licensed plumber in MA so can't do the work) and even HE recommended that I stick with an indirect because the increased cost of the EK will take too long to pay for itself if at all.

I haven't closed the door entirely on putting in an EK tank, but the clock is ticking and I don't have the time to spend trying to make this happen when a good enough solution is right in front of me.

thomase00 · August 5

Technical question:

I keep hearing that the HX can be installed in the bypass or as a separate zone. What are the advantages and disadvantages or doing it one way or another, considering that I already have an existing indirect zone?

If the HX is in the bypass, it seems that this wouldn't be compatible with the pre-piped setup from EK which has the HX right next to the tank.

Getting to the point, IF I were to convince this plumber to call EK and ask about their tank, which way would they likely recommend it to be piped? Here is a picture of my current setup:

The indirect zone is the left-most zone valve. All the zones including the indirect are piped with 3/4 copper, and the GC's plumber says the HTP SSU-45N will need 1" instead. I also need a DHW expansion tank, which the original installer neglected to put in.

mattmia2 · August 5

It was hard to tell in the small picture, but I think that brass at the pressure reducing valve for the house is 1/2". Typically residential water meters are 5/8" so the 1/2" piping around it is probably just fine.

I'm sure @Roger will answer your hx question.

thomase00 · August 5

Here is a closer picture of the PRV from the side. The outlet is to the right and the pipe threaded into it looks noticably thicker than the 1/2 pipe running perpendicular above it for irrigation. I'm pretty sure that the vertical section after the 90 to the right is 3/4, and it appears to be the same diameter as the pipe threaded into the PRV outlet.

mattmia2 · August 5

This looks like a 1/2 npt x 3/4 copper reducing ell. Remember the wall of brass and steel pipe is much thicker than the wall of copper pipe so 3/4" brass is quite a bit larger od than 3/4" copper pipe.

thomase00 · August 5

Oh I didn't realize that the pipe connected to the outlet was brass and steel! That makes sense. Will I get better flow in the house if the PRV is changed to 3/4"? The street pressure is 100psi, but I've never been thrilled with the fixture flow rates in the house, even at 60psi. Not sure if it's the PRV, distribution sizing, or built up deposits reducing flow somewhere.

mattmia2 · August 5

It is brass but brass and steel pipe are both the same dimensions. Look at the aerators in the fixtures before you get carried away, they could be clogged or if they are relatively recent they may have significant flow restrictors in them, usually a little o-ring.

thomase00 · August 5

Already done that. Before the demo, my kitchen sink was about 30' away from the main entering the house. About 23' of the run was 3/4 and then reduced to 1/2 for the last 7 feet. Even after entirely removing the flow reducer, I only got 1.5gpm. I also tried a bunch of different limiters in the same faucet but the actual GPM was always noticably below advertised, even with the aerator removed.

mattmia2 · August 5

I think there is a screen in that pressure reducing valve too. Look at the specs, not sure what the flow rate is for that valve but 1/2" pipe should supply a single fixture without a problem.

hot_rod · August 6

The way to test that PRV is to install a pressure gauge, somewhere, anywhere in the house. Get one that connects to a hose bib

See what the pressure reads

Next start opening some faucets and observe the pressure change

This is called fall off pressure test. Ideally with everything flowing, it should only drop 7 psi.

If it drops quickly with only a few faucets running, check the strainer under the first brass cap on the PRV

Generally you have a flow obstruction when pressure drops quickly. Or you are trying to flow a lot, over 6-8 gpm all at once

Here is the fall off pressure chart, and a pic showing the screen

thomase00 · August 6

I have a slop sink in the basement piped with 1/2 pex. I also have a pressure gauge mounted on an outlet close to the main with a quarter-turn valve. Just now, the pressure started at 76psi. When I turn on the cold water at the slop sink, it drops to 40psi. When I turn off the water, it goes up to 60psi and climbs very slowly after that. Could the slow pressure increase be due to thermal expansion from the hot water? Also, I'm pretty sure the screen in the PRV is clogged, we have had tons of brown water lately due to water main replacements going on in town.

mattmia2 · August 6

you will only get a pressure increase from the water heater if the boiler is firing and heating the water heater, so if it isn't firing it is probably because the seat in the pressure reducing valve is leaking. does it keep increasing over longer periods of time or does it eventually stop? as the pressure differential decreases a marginal seat might stop leaking.

that much of a pressure change is going to make it seem like you have a lot of flow at first that suddenly slows down which will be rather disappointing and probably indicates that the strainer is clogged.

Larry Weingarten · August 6

Hi, I'm my area PRVs often last only around five years, then fail with just the symptoms you describe. If this happens with no water heating taking place, the PRV is leaking pressure. Also as @mattmia2 says, that's a big pressure drop and it seems something is restricting flow. It could be a screen in the PRV. 🤔

Yours, Larry

SuperTech · August 6

@thomase00 why are you so concerned with what the plumber and GC want to do? They aren't going to be living there after they finish the work.

Get the water heater that works best for you and your boiler. That would be the EK storage tank with the plate heat exchanger.

hot_rod · August 6

Sounds like an obstruction.The strainer in the PRV is where you should start.

You could take a 5 gallon bucket and see what the flow rate of the slop sink is. Even at a 5 gpm flow it should only drop 7-8 psi.

It is normal for the PRV to increase to setpoint slowly at the end.

How old is the PRV? They can be rebuilt, or probably replaced for not much more $$

thomase00 · August 6

I've had the house for 16 years. I've already replaced the PRV once, but it don't remember how long ago. Should I replace with 3/4" PRV?

I adjusted the PRV nut and now it's staying at 60psi.

Cold water at slop sink is roughly 3.3gpm with a 20psi pressure drop. Cold and hot together simultaneous at the slop sink is about 5.5gpm with a 28psi pressure drop.

szwedj · August 6

@thomase00 In regards to your question about whether to mount the plate heat exchanger in the boiler bypass or as a zone, mounted in the bypass is the standard and most common setup and typically works very well. If you look to right of the tridicator gauge in your photo, you will see a set of unions connected with some copper. That is the bypass and those unions are where the plate would go. When mounted there, anytime the boiler fires for heat or hot water, water flows through the boiler side of the plate. When installed as a zone, the only time water flows through the plate is during a hot water call. This is typically beneficial in locations with hard water.

That said, EK offers a pre-piped tank option where the plate, domestic circ and piping are pre-piped to the tank at the factory. It's a time savings for the install and has become pretty popular with installers. Since you already have an indirect, a pre-piped tank would be the fastest and easiest choice. Just connect the supply and return from your indirects coil to the boiler side in and out on the plate and the make-up water connection similarly at the bottom, connect the wires to the aquatat and you are done.

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

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