How Much Space for EFM 520?

windyhill4.2 · Post by **windyhill4.2** » Mon. Oct. 19, 2015 9:12 pm

A mixing valve wastes heat ? HOW?My simple understanding of how a mixing valve works ~~~~ turn on the hot water spigot,hot water flows thru the mixing valve where enough cold water gets mixed (into the tap water) to keep dhw at the preset temp. Now an expert can set me strait as to where I am wrong.

Post by **StokerDon** » Mon. Oct. 19, 2015 9:22 pm

coal stoker wrote: Like I said I am not familiar with a flow check but if a circ. can push past it is it just for preventing reverse flow?
I know the zone valve seems redundant, but if I invest in the zone valve I am isolating the loop.

If your zone pumps are on the supply side, you have a "pump away" system. The flow check is for eliminating FORWARD flow when not wanted, not REVERSE flow.

My system was a two zone "pump away" like yours. One house zone, one DHW zone. After firing it up for DHW in the warmer months, it was fine. As soon as I started getting heat calls, the DHW got very hot! I searched the forum and found a term called "ghost flow". This is when one zone pump comes on and causes flow in an adjacent zone. The flow check was the cure.

-Don

Post by **Rob R.** » Mon. Oct. 19, 2015 9:26 pm

It appears that your Efm lines are tied into the return header on the oil unit, and there is a ball valve between them. Is that ball valve currently closed?

coal stoker · Post by **coal stoker** » Mon. Oct. 19, 2015 9:34 pm

I am tied into the supply side with a isolation valve.
The idea being to send heat to the load then back through the boiler through the return header and back to the efm return which is where the inter-boiler circ. is.
I know the pics are not great but trust me this is how it is plumbed.
and yes the isolation valve is 100% closed.
Thanks, CS

Post by **Rob R.** » Mon. Oct. 19, 2015 9:37 pm

There is no need to have a circulator between the boilers, AND a closed valve to divert the flow. Open that valve, then the Efm will just circulate through the header without impacting flow through the zones.

vermontday · Post by **vermontday** » Mon. Oct. 19, 2015 9:44 pm

Rob's suggestion sounds like an easy thing to try.

For the long term, does he really need the inter boiler circulator? Would the zone circulators be able to push through both boilers? Could he replace the inter boiler circulator with a straight through nipple?

coal stoker · Post by **coal stoker** » Tue. Oct. 20, 2015 5:04 am

Looks like a positive result from opening the isolation valve Rob mentioned, DHW temp is down and manageable.
Thanks Rob and all.
CS

Post by **Rob R.** » Tue. Oct. 20, 2015 5:19 am

Don't you love it when the fix is simple and free?

vermontday wrote: For the long term, does he really need the inter boiler circulator? Would the zone circulators be able to push through both boilers? Could he replace the inter boiler circulator with a straight through nipple?

It depends. The extra piping could reduce the flow rate through the zones enough to make a difference, or maybe not. The extra circulator with adjustable speeds allows you to "tune" the system, and ensures that there is always a decent amount of flow going through the EFM.

coal stoker · Post by **coal stoker** » Tue. Oct. 20, 2015 5:26 am

Yes I love a quick and easy fix.
Free is the best part.
Thanks again,
CS

Post by **StokerDon** » Tue. Oct. 20, 2015 6:53 pm

Good shoot'in there Rob. I like easy fixes. Sometimes there not obvious though.

-Don

coal stoker · Post by **coal stoker** » Sun. Oct. 25, 2015 1:01 pm

Looking for some advice as to why I am still having pressure above the rating on the pressure reducing fill valve.
I have changed the fill valve and I also put a new expansion tank in the system. While I had the system pressure down I checked the pressure on the tank and found water on the air side, hence why I have a new expansion tank.
Now when I found this and had also changed the fill valve ( 12-15psi ) I thought I had the problem figured out, but upon refilling the system my pressure still climbed to about 23psi.
I removed some water and brought back down to 20psi. and that is where I am now.
Any thoughts?
CS

Post by **Rob R.** » Sun. Oct. 25, 2015 1:17 pm

It is pretty common for the system pressure to creep up a few psi when you fill it cold, and then bring it up to temperature. If your expansion tank is marginally sized, that will contribute to it also. A pinhole leak in the tankless coil (if in use) or indirect water heater will also cause the pressure to rise, although it usually keeps rising until the relief valve opens.

What size is your expansion tank?

coal stoker · Post by **coal stoker** » Sun. Oct. 25, 2015 1:20 pm

I have a new extrol 60 on the oil side and I added a extrol 30 on the coal side.
The new 60 was purchased to replace the 30 but with the leak it replaced the existing 60.
CS

windyhill4.2 · Post by **windyhill4.2** » Sun. Oct. 25, 2015 2:12 pm

What psi was in the tank b4 install ??

coal stoker · Post by **coal stoker** » Sun. Oct. 25, 2015 2:13 pm

15 psi
on the tank before install
CS