Leave feed valve open or closed?

delcrossv

House has a conventional system piped in like how it appears in the B&G Airtrol manual (compression tank and Airtrol).

There's a manual shutoff before the PRV on the fill line.

Question is, should I leave the manual valve open or closed during the heating season ? There should be no reason to add water. Heard both ways.

GroundUp

There is no reason to add water unless there is a leak somewhere. If one appears and the feed valve is open, it may cause a bunch of corrosion due to constant oxygenated makeup water being added, or even a flood condition if the leak is bad enough. I would advise you to leave it off.

leonz

NO, leave it shut, even in the off season.

EdTheHeaterMan

As a rule I would leave the feed valve open and let the PRV add water as needed for the first week or so. That way if there is any water or air leaving the system, you have the water being replaced to keep things operating. Once the job's paid for in full, you can experiment with leaving the manual valve closed. I have has success on 70% of the jobs I installed with leaving the fill valves closed.

On the other 25% I just leave the feed valve open and look for any leaks as the years go by. Eventually there will be a valve packing that is on an old radiator that gets some mineral deposits that show up, or a threaded fitting that has been barely leaking over the last 50 years. Those leaks are not your fault and should not be the reason for you to worry about the system. When you find the leaks, you can offer a price to fix them and let the customer decide if that is worth the expense.

After the first few weeks, if I have a reason to stop by, I might close the valve, or I will close the valve at the first years maintenance check up. If the system stays operating for the year after that, then I may just top off the expansion tank with a shot of compressed air and some additional water pressure as needed. But that is just a maintenance item that is check every year, but not always adjusted.

hot_rod

If you leave it off, add a low water cut-off safety. Check that switch yearly also

DCContrarian

What Ed said. To add, if you have an air eliminator it will take a few days for all the air to work its way out, you'll need makeup water while that happens.

If a system routinely needs makeup water that's a sign that there's a problem, I'd rather be aware and deal with it than let it go undetected.

If the system has glycol in it you should close the valve and take the handle off and hide it.

hot_rod

It has a compression tank? If so as air comes out it goes into the tank. Monitor the pressure, it will move up and down a bit as the system heats and cools.

If you see a large pressure increase, good chance the tank is water logged.

delcrossv

https://forum.heatinghelp.com/discussion/comment/1811330#Comment_1811330

Yep. Compression tank with an Airtrol, so it shouldn't waterlog. I did install a Drain-o- tank, just in case. Max pressure, hot with pumps off was 24 psi on my Caleffi gauge, not the tridicator. Min was 12 (cold). I let out a pint or so so it would max out at 18psi and left the feed valve closed. I'll recheck static this week.

hot_rod

cold fill 12 psi at 60 degrees, rising to 20 at 180f. That is a good working range.

delcrossv

Hi limit is set a little high. I'll throttle it back some and see how it performs.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1811538#Comment_1811538

Some systems operate fine at 160°F as long as the weather is mild. When the outdoor temps get close to the design temp (coldest day of the year) then the boiler will cycle on the limit and the water temperature of 160° in the radiators may not be enough to keep the room temperature at the thermostat set-point. If this is a customer, and you try this experiment for them, you may save them some money in operating cost. Just be prepared to get the "Not Enough Heat" call or that "Thermostat is not keeping up" service call on a cold January night at 11:00 PM.

If that happens and you need to get out of bed to make that aquastat adjustment, That will teach you the hard way to leave well enough alone.

Ask me how I know?

delcrossv

https://forum.heatinghelp.com/discussion/comment/1811543#Comment_1811543

I think 195 seemed a little excessive. Dropped it 10 degrees and the system seems happy. 20 psi at max temp now.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1811555#Comment_1811555

You are correct. 195° is higher than I would start with, however, there have been times that I have returned to the scene of the crime to bump that temperature as high as 200° to get the rooms to the desired temperature. But for the most part, 180° was my default starting point.

delcrossv

@EdTheHeaterMan . Went by tonight and opened the feed valve. System seemed stable, so I'll recheck the static pressure tomorrow. Did take up some water,but I did previously take some out as the pressure was getting pretty high (mid 20's). That hasn't repeated, so I'm at a loss to explain it.

Boiler did fire with no load, so the low limit on the aquastat is working.

Now it's running 14 psi warm and 18 psi hot without any pumps running with the feed valve open. PRV is warm, so it's closed.

EdTheHeaterMan

Since the boiler is operating on a low limit to maintain a temperature, you probably have a tankless coil for the DHW. Let me know if that is the case. (Do the hot and cold water pipes go into a plate on the front of side of the boiler?)

delcrossv

@EdTheHeaterMan

Nope, no coil or DHW, ever. Stopped by this morning on the way to work. 15psi, boiler is warm, no zone calling.

EdTheHeaterMan

Then you do not need to maintain a water temperature. Remove the low limit and use a relay to bring on both the pump and the gas valve from a cold start. That will reduce your gas usage by 10% to 20%.

delcrossv

House looks like it'll be sold soon so I'm good for now.