heating hot water with outdoor boiler

Congrats on the little one! Went to the website to hunt up a manual but apparently not available. Been too long since we had an OWB that I can't remember set-up details well. We never had our hot water hooked up so we didn't have to run it in the summer... went electric for that.

Welcome to Hearth! What type of DHW heat exchanger do you have, flat plate or sidearm? What type of heat emitter/s in house, do you have DHW plumbed before or after your emitter? Do you by chance know the temp of the water going into the house, or flow rate? Does it heat the house properly, but not the DHW, is the water not hot enough, or just slow to recover? Lot of variables that are needed.

Or, If the mixing valve is properly installed on the output of your water heater, just turn it up a bit. They have a temperature range that they will mix to.

you should be able to adjust the mixing valve to get hotter water.

Any mixing valve I have seen has an adjustment on it.

Although the cheaper ones don't always work the best.

We don't know anything about your current setup - pictures?

That looks like a decent mixing valve, the gray knob on the top sets the temp. Are you sure it's set for full hot? Or is it set for full mixing?

But something still seems off. Are you heating the hot water right now & all summer with the OWB? Does the OWB pump run 24/7? Was the DHW hotter in the winter when also heating the house, or was it not hot enough then too? If the pump is running 24/7, nothing really should have changed between winter & summer as far as how hot your DHW is getting - unless maybe your sidearm is scaling up inside & needs flushing. Some temperature measurements in certain spots would help - like in & out of both sides of the sidearm, and maybe also tank temps.

I have my system all set up for heating DHW all summer with my wood boiler, and it does it very well - I can go a week between burns. But even at that, I have gotten to the point where unless I have a bunch of junk wood to get rid of over the summer - I just let the boiler go cold & the electric water heater do the job when not also heating the house. It's worth the $20-25/mo of electricity to me to avoid burning that much of my good wood for 4-5 months.

The mixing valve could be broke. Does your boiler have anything that shows the water temperature? Is you water circulated through with a pump, possibly moving water too fast?

Mixing valves in a domestic hot water application tend to calcify and become frozen at any particular position causing the output temperature to be anywhere on the scale. You need to read the temperature of your water at the output of the tank ahead of the mixing valve.

riverrat424 said:

I bought the stove least year before putting the mixing valve in I turned it all the way to hot. Last winter I used one of them laser temperature guns at the point where it comes into my house and it read like 175 f. I talked to a guy that said to put a screw valve just before the mixing valve on the cold side an limit how much cold comes into mixing valve any thoughts on that?

Click to expand...

What is that mixing valve rated for temp wise? 140, 120, or lower maybe? Sounds like it is a low temp one. Get one that you can set the temp up to 140

riverrat424 said:

I bought the stove least year before putting the mixing valve in I turned it all the way to hot. Last winter I used one of them laser temperature guns at the point where it comes into my house and it read like 175 f. I talked to a guy that said to put a screw valve just before the mixing valve on the cold side an limit how much cold comes into mixing valve any thoughts on that?

Click to expand...

If you really want to know what's going on, you need to accurately measure temps at 6 places - in and out of each side of the sidearm, and in & out of the mixing valve.

You could put a ball valve in the line that sends cold water to the mixing valve, and throttle it down until you get the desired hot temp coming out. I used to do that when I was heating DHW with oil & tankless coil and turned my boiler down in the summer. But if the sidearm isn't getting your water hot enough to start with, then that won't help & you still won't know what the issue is.