Tankless coil Replace or Remove?

[Deleted User]

that the relief valve is good? i'd change it, easy/inexpensive, before going any further

Larry C_19

Tankless Coil Replace or Remove?

Folks,

Home owner here. I have a eight year old Peerless EC-05 cast iron boiler with a Beckett RWB burner and a Therma-Flow PF-5 tankless coil. Recently I noticed a couple of things. First the boiler water relief was lifting. Also I heard gurgling in one of the baseboards. Today I removed the Extrol 30 expansion tank to determine if it was solid. It was not. I also removed the two air vents and boiled them in vinegar to clean them up. After reinstalling the air vents and purging the system of air, one of them is still leaking, so it remains capped off.

The next thought to cure the relief valve lifting was to eliminate either a tankless coil leak or a leaking make up water valve. I isolated the tankless coil, drained it and let it sit for an hour. When I flushed water back thru it I got a slug of hot steaming rusty water.

I assume I found out that the coil has a pinhole leak. I will leave the coil isolated overnight to verify that the coil fills back up with rusty water again, and see if the relief lifts again.

The system is not plumbed for pumping away. Three zone pumps, one for each zone, pump into the boiler, The expansion tank and one air vent is on the boiler output. After the expansion tank, there are three, three port Taco check valves. The capped air vent is screwed into the top of the boiler. Except for the near boiler piping and the boiler itself, the rest of the system is copper.

Does it make sense to just live with the leaking coil thru the winter, replace the coil, or remove/cap the coil and install a external water heater zone?

Does fixing the non pumping away configuration save any fuel or significantly extend system life?

Thanks,

Larry C

PLUMBARIS

Pin Hole Leak

I do not know how you could just live with the pin leak. If you cap off your coil you have no hot water and if you leave it you will have a constant relief leak and be adding fresh water constantly to your boiler, neither is an option I would care to live with. My vote is for an indirect on a fourth zone, this will save you alot of money in the summer months by not maintaining boiler temp all summer. As for the pumping away, its great and helps a system purge easier, ect. but there are thousands of systems out piped diferantly that work fine. If Iwas changing the boiler I would change the piping but not just for the heck of it.

Larry C_20

Thanks

PLUMBARIS,

Thank you for the quick reply. This morning there wasn't any rust in the indirect coil when I flushed it out, and I had to hook the HW back up again. I could not tell if the relief let loose again last night. The boiler is in the basement with a dirt floor (100+ year old house).

I will stick a bucket under the relief valve pipe and check it for water.

Is the coil made of steel pipe? Could the rust just have been internal corrosion of the coil?

Thanks.

maine rick

first off whats the pressure in the boiler- above 30lbs relief valve will blow, below it will not.
coil is copper. if you can find a pin hole leak in the coil good luck for i replace them.
as far as the rust color water from coil that tells me you have well water not city. when you cut and flush a coil you remove some build up of the water contant,hen's the rust color.
so
1-check your pressure
could be bad relief valve or you fast fill is seeping water by and building your pressure above 30lbs.
hope this helps

Larry C_20

More Answers

Water is city water, not very hard. All of the in-house piping is copper. Material of the water mains, unknown.

Assuming the dual guage is resonably accurate, the relief is lifting around 30 psi.

If I were to install an isolation valve for the make up water feeder, would I put in downstream of the regulator or upstream of the back flow preventor?

Thanks,

Larry C

maine rick

if you add shutt-offs i would put one before and after this way you do not have to drain the boiler when you replace.
close the fast fill lower the presure to 15 lbs,turn the heat on watch the gage if it climbs change your extrol tank

Larry C_13

More Answers II

This morning when I went to check the boiler, the relief valve had lifted.

I'll get two ball valves and install one between the fill regulator and the boiler outlet piping, and the other valve upstream of the backflow preventer. This will allow me to isolate the fill valve without disabling the indirect coil.

Larry C

PLUMBARIS

Isolation

Are you sure there isn't a valve upstream of the fill valve already, fairly rare not to be. Throw in a union between them also for future srvice.

TimS

shut off the cold supply to indirect water heater leave hot water faucet open for some time shut off make up water to boiler then wait will boiler pressure hold at 15 psi or slowly move up to 30 or drop low boiler can be shut off duringthis test.

Larry C_13

fill Valve isolation valve

The upstream isolation valve for the feed valve is also the isolation valve for the indirect coil and tempering valve. Therefore I can't isolate the feed valve without isolating the indirect coil. However I can isolate the indirect without shutting off the feed line.

The backflow preventer assembly is made up with unions.

Larry C