Temperature setting and mystery shutoff valve

pikachu1234

Hi I'm a new homeowner trying to figure out the existing boiler system. Recently, the circulator pump zoned to the indirect water heater from the boiler started making extremely weird and loud noises. The zone for it was always being called and I think the water wasnt pumping correctly so the noises occurred. When looking at the aquastat on the water heater I started to just play with it not really knowing what I'm doing and currently I have it set at 120 which kind of fixed the problem but the noise is still weird and loud humming sound.

The question i have is:

1. Is 120 on the aquastat a proper temperature with a differential of 10? Does it call for the water exchange/circulator pump when the temperature gets below 120?
   
2. Does the pump need to be replaced?
   
3. The actual boiler has it high temperature set to 171, so how does this work if there's an aquastat on the water heater at 120? Does it matter what the boiler has the high temperature set at?
   
4. I have a weird shut off valve in the picture on the left circled in yellow. It is for a pipe from the boiler to the water heater on the picture on the right but not sure. It is in the shut off position so I'm not sure if I had done that by messing around or it was already like that.
   

Jamie Hall

Having the aquastat on the water heater set at 120 on with a 10 differential is common enough, and if there isn't a mixing valve on the water heater outlet you don't want it set any higher. A more recent setup would probably have a mixing valve, to avoid scalding, and run the water heater hotter. But that's optional.

Now what should happen is that when the water heater temperature drops too low that aquastat should click on and the associated circulator should turn on and hot boiler water should circulate through the water heater and you get hot water.

So. First question: do you still get hot water from the water heater? If so, you must be getting circulation through it, weird noises (which, incidentally, are not good) or no.

Second question. does the circulator for the water heater shut off when the water heater is hot enough, or does it just keep on going all the time? If it does, I would think you might be getting very hot water -- which is dangerous. As well as not operating correctly.

The boiler has a different aquastat, and that is set to maintain the boiler water at a high enough temperature to heat the house -- and, not incidentally, the hot water heater. You don't want it set higher than it needs to be, but somewhere around 170 is common enough. You can tell -- again, this is an older control setup, though perfectly good -- if the boiler can heat the house on the coldest days. If so, you're good.

Without being able to see all of the piping runs and tracing them, I haven't a clue as to what the valve that's shut off is supposed to do. It may be a feed to the boiler itself. If you are getting hot water and heat, I'd leave it alone until you can trace all the piping and see what it connects to what.

As to your question 2. Without actually hearing the pump -- or feeling it -- it's quite impossible to tell whether the pump needs replacing or if it simply has some air in it. A related question, though: there should be a pressure gauge somewhere on the boiler, and I'd kind of like to know what pressure it shows.

pikachu1234

Jamie Hall said:

Having the aquastat on the water heater set at 120 on with a 10 differential is common enough, and if there isn't a mixing valve on the water heater outlet you don't want it set any higher. A more recent setup would probably have a mixing valve, to avoid scalding, and run the water heater hotter. But that's optional.

Now what should happen is that when the water heater temperature drops too low that aquastat should click on and the associated circulator should turn on and hot boiler water should circulate through the water heater and you get hot water.

So. First question: do you still get hot water from the water heater? If so, you must be getting circulation through it, weird noises (which, incidentally, are not good) or no.

Second question. does the circulator for the water heater shut off when the water heater is hot enough, or does it just keep on going all the time? If it does, I would think you might be getting very hot water -- which is dangerous. As well as not operating correctly.

The boiler has a different aquastat, and that is set to maintain the boiler water at a high enough temperature to heat the house -- and, not incidentally, the hot water heater. You don't want it set higher than it needs to be, but somewhere around 170 is common enough. You can tell -- again, this is an older control setup, though perfectly good -- if the boiler can heat the house on the coldest days. If so, you're good.

Without being able to see all of the piping runs and tracing them, I haven't a clue as to what the valve that's shut off is supposed to do. It may be a feed to the boiler itself. If you are getting hot water and heat, I'd leave it alone until you can trace all the piping and see what it connects to what.

As to your question 2. Without actually hearing the pump -- or feeling it -- it's quite impossible to tell whether the pump needs replacing or if it simply has some air in it. A related question, though: there should be a pressure gauge somewhere on the boiler, and I'd kind of like to know what pressure it shows.

Thank you for the thorough response!

1. I still get hot water
2. 2. It does shut off but I'm not sure if it shuts off properly. When it is running, the temperature of the boiler is around 190, higher than the 171 that it is set to, not sure if that has to do with anything. When it is not running, the boiler temperature drops to like 108. The pump gets super hot and it just stays on for prolong periods but the pipes around don't really get hot, just warm, so I believe that its running but no water is really passing through.
3. 3. The pressure gauge is showing about 0.

I have a burham es2 boiler.

Jamie Hall

The pressure gauge is around zero? Not good. Should be around 15. See if you can find out where water gets from your domestic water supply into the boiler itself -- not the hot water supply to the house, but a pipe from your water supply to the boiler. And see if there is a valve on it (It may be that odd one you circled) and try opening the valve a bit and see if the pressure changes.

And come back...

pikachu1234

Jamie Hall said:

The pressure gauge is around zero? Not good. Should be around 15. See if you can find out where water gets from your domestic water supply into the boiler itself -- not the hot water supply to the house, but a pipe from your water supply to the boiler. And see if there is a valve on it (It may be that odd one you circled) and try opening the valve a bit and see if the pressure changes.

And come back...

I turned it on and the pressure on the boiler is steady at 20. So when it was off, the boiler was not getting domestic water?

Jamie Hall

The pressure should be around 15 to 20 when the boiler is cold, and perhaps a few pounds higher when it is hot. You shouldn't need to add water, however, unless the system has a leak somewhere.

If the pressure is good when it's cold, but rises a lot when it heats up -- or it's good when it's hot and drops very low when it's cold, that may mean that your system's expansion tank -- somewhere on the heating piping near the boiler -- needs attention.

Now another question -- when the boiler pressure is at 20, does that pump still make funny noises?