Re-doing hydronic piping on oil-fired boiler

TViapiano

Hello. I have a Weil McLain Gold Oil P-WTGO-4 boiler that provides hydronic heat to baseboard radiators and also provides domestic hot water via a tankless coil. There is one Taco 007 series circulator that feeds two hydronic zones using Taco zone valves.
The boiler is at least 18 years old (it was here when I bought the house 18 years ago) and the only major issue I’ve had is the burner was replaced 1 1/2 years ago because it was not running well - intermittently having trouble starting up and producing puffs of smoke.

The house is a 1500 sq. ft. single story ranch style with a full basement.

I’d like to change from zone valves to separate circulators for the two heating zones and add a third priority zone for an indirect water heater.

I purchased and read the book “Pumping Away” and it was a great resource.
I tried to research my particular boiler, but I could not find a reference to how my boiler is plumbed with the circulator attached to the tap in the front of the boiler. It is pumping away as it should, but I’d like to install the 3 new circulators to the right of the boiler with a nice new plywood backboard to mount everything, etc.
The feed valve connects to the tee in the iron pipe at the top right of the boiler where the expansion tank is connected. The return to the boiler is the usual place in the front lower left tap. The T&P valve is in the back of the boiler.






So here are my questions:

Because I’d like to mount the circulators over to the right of the boiler, using the existing front tap that the circulator is connected to would require the piping to cross somewhere in the front of the boiler and would be in the way.
Can I use the top right tap as the feed to the circulators and simply cap off the top front tap where the circulator is now?

Would I still keep the feeder valve and expansion tank on that same top right tap as well?

Can I install the indirect water heater several feet away from the boiler so that it is closer to the points of use for faster hot water to the taps? I asked my oil delivery/technician about that and he said the indirect has to be close to the boiler, but if it’s possible I’d like to have the indirect about 15 feet away where it would be right below the back-to-back bathrooms and very close to the kitchen.

When I move the hot water source to the indirect water heater, what should I do about the tankless coil? I would think that simply capping the connections could cause a pressure build up in the coil when the boiler is heating. Should I just remove the fittings and leave it open?

Thank you very much for any guidance you can provide.

EBEBRATT-Ed

use the top right tapping for the supply

expansion tank and feeder... yes. Picture removing the reducing elbow the expansion tank is connected to and putting a tee in it's place. The other side of the new tee feeds the supply to your circulators. The city water make up goes in the system at or near the expansion tank location.

That boiler has a tapping on top of the boiler for an air vent. No need for any other air removal devise.

15' away for the indirect is fine.

Leave the coil connections open

hot_rod

How many feet of baseboard do you have? Seems like a lot of boiler for 1500 sq ft?

One ECM pump and 3 zone valve is another good option, 1” piping and zone valve for the indirect.
I would add a good Air/ dirt/ magnetic separator, especially if you go with one or three ECM circulators. Out of boiler, thru Sep, zone valves to loops
purge valve on return at the boiler

mattmia2

Note that your current circulator is pumping in to the boiler, not pumping away from the boiler.

TViapiano

Thanks everyone for the information.

The circulator and zone valve arrows appear to indicate that the circulator is pumping away from the boiler:




Here is a better view of the top right tapping, make-up water feed, expansion tank, and air vent at the very top:



So if I move the circulator(s) to this tapping, I should be okay to just plug the front tapping?

The baseboard heater lengths are:
1st zone - main part of house: 1 inch line runs from the zone valve to the far end of the house and tee's into two 3/4 inch lines to feed the front and rear exterior walls of each room and then back to the boiler: 51 feet total baseboard length

2nd zone - small-ish old addition (that I gutted and re-insulated when we bought the house): 3/4 inch line single loop - 31 feet total baseboard length

Thanks again.

mattmia2

Where is the return? Is that at the lower left corner of the front?

I strongly suggest you find the manual for the boiler and read it if you haven't.

EBEBRATT-Ed

@TViapiano

Like I posted before.

If you take the reducing elbow off the top of the expansion tank and replace it with a tee remount the expansion tank where it is, move your pumps to this connection pumping away from the expansion tank then out of the pump(s) to your supply pipes you will be fine. Since you have (or will have) two pumps install flow check valve downstream of each pump (unless your pumps have internal check valves)

Plug or cap the old supply connection at the boiler

TViapiano

Thanks again.

@mattmia2: Yes, the return is the front lower-left tapping.
Thanks, I will definitely try to find the manual.

@EBEBRATT-Ed: Thank you. Yes, everything that you originally posted makes 100% sense to me, I was just unclear about what to do about the font tapping and if I could plug it. Having the manual as mattmia2 suggested would have helped me with that question.

I will be doing this work probably sometime next month once the heating season is over here in the Boston area. I will post an update here once I am done.

Does anyone have a suggestion for a brand of indirect water heater? If that's not allowed on the forum I understand.

Thanks!

mattmia2

Htp superstore and weil mcclain are 2 to look at that are stainless steel. Look at your water's chloride content and the specs of the tank if you go with stainless. There are conventional glass lined tanks from the usual suspects like rheem and ao smith.

TViapiano

Thanks again @mattmia2, I will look into those.

And, I found out why I never looked through the manual for the boiler: I can't find one that matches my boiler - with the large tapping in the front. In fact, the way I found this forum in the first place was from this post because the boiler appears to be the same style as mine:
https://forum.heatinghelp.com/discussion/168469/what-looks-wrong-with-current-boiler-installed

I can't find a WM boiler manual that has the large tapping in the front.

mattmia2

That front tapping is probably mainly used when it is set up with steam trim.

EBEBRATT-Ed

@TViapiano

The top tapping that the expansion tank is connected to is the correct tapping for the hot water supply. I don't know why they used the front tapping for the supply.

EBEBRATT-Ed

@TViapiano

I don't think that front tapping exists on the newer model of that boiler. It looks like the location of the "skim tapping" if used on steam. Perhaps back in the day they used the same boiler for water or steam and have since changed the tapping's.

Either way just plug it ....no issues

TViapiano

Thank you @mattmia2 and @EBEBRATT-Ed. I really appreciate it!

STEVEusaPA

What's wrong with the draft that you need this? Maybe a real proper cleaning, and properly sized nozzle (not underfired) may help. I'd bet there is an O.F. draft problem (maybe positive).

EdTheHeaterMan

mattmia2 said:

Note that your current circulator is pumping in to the boiler, not pumping away from the boiler.

mattmia2 said:

Where is the return? Is that at the lower left corner of the front?

I strongly suggest you find the manual for the boiler and read it if you haven't.

mattmia2 said:

That front tapping is probably mainly used when it is set up with steam trim.

Looks like a lot of good info here. Here is a page from the WTGO Series 1 boiler instruction manual.

in the Series 2, 3, and 4... The circulator is installed on the right top supply tapping. Just where you want to put it. (BTW the front tapping is a good place to skim the SGO boilers, same boiler with steam trim).


After you install the indirect, don't forget to tell the boiler to stop making hot water. The pipes let you use the hot water it makes in the tankless coil. By disconnecting the pipes, you cant use the hot water the boiler makes anymore... But is will still make the hot water unless you tell it to stop. That is done in the control logic. It is easily done, but many forget to do it. Ask me How and i'll tell you.

rick in Alaska

That front tapping with the pump out of it was on the first series of the wgo line, and then it went away in the later series changes. I believe the one shown with the front tap also had the relief valve piped out the back; what a pain that was. Luckily the people at Weil Mclain listened to our complaints and changed things.
Rick

geno907

This is a super neat project. Be careful how much you change around. Although it’s cast iron, tried and true, changing a bunch of stuff will have a high chance of burning up your pump.

What makes you want to change the design besides the fact you’re pumping into the point of no pressure?