Low Hot Water Pressure Questions

Low Hot Water Pressure Questions

PostBy: bsarte On: Wed Jan 11, 2017 10:41 pm

Hello Everyone,
Please forgive my ignorance on this subject -- but I am at a loss for why this is going on.

Recently -- say, over the past month to six weeks -- we have had a serious reduction on hot water pressure in our house. Cold water is fine -- but there is very little hot water pressure. So much so, that showers are almost a waste of water. I have checked the hot water line between the boiler and shower (which is the end of the hot water line) and there are no leaks. I have fully bled the radiators, they are all set.

Where I get confused is the summer/winter water heating -- I do not have a grasp on how it really works and maybe that's part of the issue... but I do not know... I don't even know what or where to look to see where that issue might be.

The water pressure in the boiler was reading 11ish -- I upped it to 15 to see if it made a difference, it did not seem to make any noticeable difference out of the faucets. Someone I had service the system a little while back said the pressure should be between 12-15.

So here are my questions...

1. How do I troubleshoot this?
2. What should the pressure be in the system?
3. What is the difference between the water that flows to my radiators, and the hot water that goes to my faucet? I see the water go into the boiler and I see where it comes out.. and I see where it goes to a holding tank... but beyond that, I'm pretty much lost.

ANY help would be appreciated immensely!
Other Heating: EMF PK750T

Re: Low Hot Water Pressure Questions

PostBy: waldo lemieux On: Thu Jan 12, 2017 12:12 am

Sounds like your water coil needs to be flushed. Im not familiar with a 750 so if you could post a couple of pics of the front , back and each side of the unit someone will get you on the right track. Promise! :D A little information on your abilities and your location will also help.

waldo lemieux
Stove/Furnace Make: efm
Stove/Furnace Model: s-20

Re: Low Hot Water Pressure Questions

PostBy: 2001Sierra On: Thu Jan 12, 2017 12:33 am

The boiler pressures you are reading are for the vessel. The boiler is a pressurized vessel. The domestic hot water passes through the vessel seperate and is at house pressure.
Hot Air Coal Stoker Stove: Keystoker 90 Chimney vent
Coal Size/Type: Rice
Other Heating: Buderus Oil Boiler 3115-34
Stove/Furnace Model: Keystoker 90 Chimney Vent

Re: Low Hot Water Pressure Questions

PostBy: blrman07 On: Thu Jan 12, 2017 5:05 am

The water pressure you adjusted has nothing to do with the pressure of the hot water. The domestic water is being heated as it runs through a coil inside the boiler. The drop in pressure in only the domestic hot water system throughout the house would be caused by a scale buildup inside the coil. With a buildup of scale it makes the interal water passages through the coil to be less and less.

I am assuming that the hot water pressure is equally bad throughout the house and not just the shower.

If it has dropped at all hot water outlets, you need a plumber familiar with chemical removal of scale from coils.
Hand Fed Coal Boiler: Bucket a Day
Hand Fed Coal Stove: Vigilant Casting 2310
Coal Size/Type: Pea/Nut/Wood in the VC and anything that will fit in the Bucket a Day. It's not fussy.

Re: Low Hot Water Pressure Questions

PostBy: Rob R. On: Thu Jan 12, 2017 6:31 am

There should be a mixing valve installed in the hot water piping just after the coil. These often get stuck due to mineral deposits, and should be cleaned (or replaced) when the coil is serviced.
Rob R.
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy