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Discussion Starter · #1 ·
Hi,

I have been learning everything I can about this system for the past month. I have a question regarding the Aquastat and hotwater loop for potable hot water.

Our aquastat which is a Honeywell L4006A is set to 180F currently. Best I can tell Burnham recommends 190F for steam boilers I assume in order to get the most out of the hot water coil.

We recently had a new mixing valve installed and the hot water coil cleaned which cured 90% of our hot water problems (new house to us).

The hot water temp still changes some during a shower. I am assuming if I raise the aquastat to 190F per Burnhams recommendation this should help if not completely cure the problem? The mixing valve is set to around 120-125F.


My main concern is I don't know the drawbacks of raising this. Burnham states 190F with a 10deg differential. Won't this cause the burner to run often?

Thanks,

Chris J.
 

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You should have another aquastat, the 4006 is probably your code required second limit.

Look for another gray box near the coil.
 

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Discussion Starter · #3 · (Edited)
Thanks for the response.

The Honeywell is the only aquastat I have to my knowledge. It is mounted right next to the coil. Best I can tell this is the ONLY thing controlling the boiler temperature as far as my hot water goes.

The only other control I know of is a Honeywell Pressuretrol which is mounted on the front of the boiler with a high and low PSI setting which is only used when the boiler is producing steam.
 

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Ok. Forgot you said you have steam.

See if it has a fixed differential or adjustable differential. Setting it to 190 will still give you water temp changes. Perhaps not as bad, but they will still be there. You are probably over tapping the coils ability.
 

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Discussion Starter · #5 ·
Ok. Forgot you said you have steam.

See if it has a fixed differential or adjustable differential. Setting it to 190 will still give you water temp changes. Perhaps not as bad, but they will still be there. You are probably over tapping the coils ability.


It has adjustable. I just set it per the boilers instructions so I'll see what happens.

The differential was around 6 and it was set for 180F. Now its set to 190F with a 10 deg differential. While this means a wider temperature range I feel the mixing valve should be able to control it better now as it should never get cooler then my high setting was before.

I'm hoping the wider differential will stop the boiler from running so often.

I also checked my water level and set it per the boilers instructions. Apparently I can cheat a little in the summer when its not making steam and cover the coil a little more.

Chris J.
 

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Do you treat the water in the boiler?
If not rust and sludge can build up and take longer to produce the domestic hot water.
 

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There are chemical additives added directly to the boiler. The chemical forces the sludge and rust to the bottom and is then able to be drawn off. This should be done annually.

Cleaning should be done by a licensed and insured heating or plumbing company familiar with steam boilers.

Think of it this way. If you had a pot of clean water and a pot of rusty/sludge water on the stove, the clean water would boil first and faster than the other with sludge and rust.

Internally, rust builds up around the hot water coil immersion tubes during operation, so the cleaner the boiler the cleaner the tubes will be and the faster the heat is produced.
 

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Discussion Starter · #9 ·
There are chemical additives added directly to the boiler. The chemical forces the sludge and rust to the bottom and is then able to be drawn off. This should be done annually.

Cleaning should be done by a licensed and insured heating or plumbing company familiar with steam boilers.

Think of it this way. If you had a pot of clean water and a pot of rusty/sludge water on the stove, the clean water would boil first and faster than the other with sludge and rust.

Internally, rust builds up around the hot water coil immersion tubes during operation, so the cleaner the boiler the cleaner the tubes will be and the faster the heat is produced.
It seems finding a heating company or plumber who is experienced with steam heat is far harder then I ever imagined. :(:(


I've used the shower since I changed the aquastat to 190F with 10 deg differential and I didn't notice any temp changes anymore. I guess the output is staying hot enough for the mixing valve to control now.

I understand why it is usually discouraged, but is maintaining the boiler as well as cleaning the inside of the block as you mentioned something a DIYer such as my self can learn in time?
 

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That is the way we all learn.
There are several old oil companies that are familiar with steam boiler operation.
Steam was really popular years ago and the last house we lived in we had steam. I think if maintained well steam is the best heat there is.

Look in the yellow pages and make a few calls to the older, larger oil companies to see if they are familiar with steam systems.
 
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