I think I have a hydronic hot water heating system, and I'm having a problem where the hot water in the faucets and showers never gets all that hot. I've heard it could be the mixing valve among other things. I've provided pictures of my system in the link below, in the first picture i circled a valve with a black knob, is this the mixing valve? Could the mixing valve be my problem? Are you able to tell by looking at the picture what the position of the mixing valve is? I appreciate any input provided, thanks.

http://home.comcast.net/~apexigsx/water/index.html

 

Hi Ape, yes, it does appear that you do have a hydronic hot water system.

Yes it could be your mixing valve, no I can't tell what position the valve is in.

I do see some things that could use some repair/maintenance (specifically that corroded and leaking connection), and what looks like a zone valve (the thing with the green top on it) installed backwards (is that arrow pointing to the left?)... and can't really reason why it's even installed there... and is your backflow preventer atmospheric vent really plugged? ... but that's all secondary to your problem.

Is the pipe running from the boiler to the mixing valve HOT! so you can't really hold it?

And the pipe leading out on the right only lukewarm?

I don't think that one is a 'thermostatic' type of valve... you might consider replacing it with one that is (thermostatic)... such as the Taco 5000 series.

Taco-Hvac: 5000 Series Mixing Valve

 

Thanks for the reply.

I plan on looking into repairing the corroded connection. I think the angle of the photos may have made the zone valve appear to be installed backwards so I have provided a new picture (or the valve could really just be backwards). It does appear that the backflow preventer atmospheric vent is plugged (model hersey bcp), as seen in the first picture on the link below. Is it bad to have the backflow preventer atmospheric vent plugged? The pipe running from the boiler to the mixing valve really isnt hot. I took another picture, and the area of the pipe with red next to it indicates I could only hold my hand on the pipe for about 5 seconds, and the part with the green next to it I could hold for as long as I wanted. So since 90% of the pipe coming out of the boiler going to the mixing valve is only lukewarm, this makes me think the mixing valve is not the problem. We do get hot water, but most of the time when I do something the water coming out of the faucet ranges from lukewarm to mildly hot. I appreciate any extra input you may have.

http://home.comcast.net/~apexigsx/water/index.html

 

Wow. It says "vent" right there and someone stuck a plug in it. I think that's there to blow off pressure in an emergency so it should not be plugged. It should have a pipe running from it down to 6" from the floor. I wonder if it was leaking so someone plugged it up. If that is the case, it may need to be replaced.

 

Ohhhh, now I see it! The photo I was looking at, the angle was such that it appeared that the zone valve was installed on the hot supply line out of the boiler. It was EXACTLY lined up!

No, I think yer all right with that part.

You could still have an issue with the mixing valve... it might just not be flowing much water through the hot port, and if there is very little flow, the pipe still won't be hot.

Those coils DO get 'limed up' with mineral deposits from the water, and when that happens they don't give much hot water. It could be that, but first make sure the valve is OK.

Aren't there any markings on the valve that indicate which direction is hot and which is cold?

The next step would be to check the settings on the temp dials inside the gray box (your aquastat) on the front of the boiler. There is 120VAC INSIDE! so, turn off the power to the boiler, slide that cover straight off after loosening the screw on the side that holds the cover, and tell us what all three dials are reading.

Also, tell us what the pressure and temperature gauge on the boiler is reading. Maybe a close up pic of it.. from what I can see, you may not have enough pressure in the system.

 

It's not good, but it's not a TERRIBLE thing that the vent is plugged on the backflow preventer. You wouldn't have a problem unless you lost water pressure in the home... which rarely happens. If that vent was leaking, it would mean that one or more of the three check valves inside that gadget is also leaking. If you lost pressure in the home, boiler water could flow back into your potable water supply. Millions of boilers installed today don't even have one of those BF preventers. Only in the past decade or so have they been required by most building codes.

(Can you keep a secret? mine is plugged too! but don't tell anyone... it started leaking about a month ago... shhhhhh.)

Chances are that thing needs to be replaced, but it can wait... I mean, the boiler ain't gonna blow or anything.

I think droo's comment about it blowing off pressure ... he was thinking about the RELIEF VALVE on top of the boiler. Don't EVER plug one of them!

 

I appreciate the replies thus far. I have updated the link with a picture of the temp gauge. That is a picture of the gauge with the boiler off and no hot water being used. I turned on the hot water in a nearby sink for 2 minutes, and there really wasn't much change, though the temp may have dropped slightly. I turned up the heat so that the boiler would turn on, and still no change in pressure at all (didn't pay attention to temp). I've periodically been checking the temp gauge lately, and I don't think I've ever seen the pressure part of the gauge move from zero. Not sure if that means its broken or what.

To be honest, before I had started this thread we arranged for someone to come and check out the boiler and try to solve our water temperature problem. I just thought I'd see if anyone here could see any obvious signs that may be causing our problem. The person should be coming by sometime within the next few days, so I'll keep this thread updated when we find out more.

 

What is that vent for on the backflow preventer?

I'm on city water so my domestic water pressure drops at least once a year when they flush the hydrants. Not sure if it goes lower than 12 psi though, but it gets really low. When I was in my apartment that had a well, we would loose pressure every time the power went out. It's not as uncommon as you think.

 

You need to determine if the gauge is broken or not. There should most definitely NOT be zero psi in the system. The MINIMUM should be 12 PSI when the boiler is COLD, and maybe as high as 20 when it is HOT.

Ya know, it could even be possible (but I doubt it because you would long ago have complained that there is no heat in the house) that your boiler is even low on water and that could cause no domestic hot water... there has to be hot boiler water surrounding the internal coil inside the boiler...

Lemmee ask ya this: to the right of the plugged backflow preventer is a tan valve, the bell shaped one... follow the pipe into that to the right and it goes down and over and what not... to a valve with a blue handle. Is that blue handle valve open or closed?

 

To be honest, this is my parents house and they don't want me touching any valves or anything. Based off looks alone, the valve definitely appears to be closed. I have updated the link with the pictures, and the first picture is now a picture of what I believe to be the closed valve which feeds water to regulator - backflow preventer - expansion tank. The picture below the 1st one is just of some random valves for comparative purposes, as the valves seen in the 2nd image appear to be open all the way.

So what does it mean if the valve going to the regulator then to the backflow preventer and up to the expansion tank is closed all the way, as it appears to be? Could the valve be closed on purpose since between the backflow preventer and the expansion tank there is a T which goes directly into the corroded pipe?

*I also wanted to add that we have zero heating issues in our home with the hot water baseboard, its just the hot water issues out of the taps. I get hot water for about 45 seconds to a minute at the start of my shower, lukewarm for 4-5 minutes, and then another 45second to 1 minute stint of actual hot water (assuming no hot water has been used recently by an applicance).

http://home.comcast.net/~apexigsx/water/index.html

 

What it means is that there is no way for water to feed into the system. Along with the leaking joint, your parents are setting themselves up for a problem... a leak letting the pressure fall, and no way to replenish.

If they don't want you touching it, then you must insist that they get someone in to repair it.

Don't they get a lot of air gurgling through the pipes every time the heat turns on?

I am going to have to assume that this is a ranch style house (1 story) because if there were a 2nd floor there wouldn't be any heat up there with no pressure in the boiler.

And for all we know, the boiler might already be only half full of water and that's the reason that there is little domestic hot water.

And when that boiler fires up with so little water in it, the boiler will probably crack and need to be replaced, and there is also a fire hazard. One must NEVER EVER run a boiler dry!

PLEASE get that thing fixed first, that is more important than no hot water. (and it might fix that too...)

 

I feel like I have heard gurgling noises from the pipes before. This is a 2 story raised ranch house. I can't really comment on the heat upstairs since I'm downstairs 90% of the time, I just know the heating works ok downstairs.

 

OK, well, you know what you need to do now anyway...

 

Just wanted to give a small update.. we spoke to the guy who did the last work on our boiler, and he said water is manually added to our boiler? I'm not sure what that means or how that would work. Any ideas?

 

hi ape –

I am not an expert like many of the guys on this forum. I’m a newbie learning here myself. But here is a link to something that explains some water makeup alternatives on hydronic systems you might read before Trooper and the other guys get back to you. I know Trooper and the guys on the forum know more than the folks on the site I reference, and they have found mistakes on that site before, but I bet the explanation I reference is pretty much correct.(I’m sure Trooper or the other guys will make corrections if necessary.)

Pressure Reducing Valves (automatic water feeder valves) on Hot Water (Hydronic) Heating Boilers

Bottom line, it seems like the guy who told you that water is added manually means that you are supposed to check the pressure often, and upon detecting low pressure you should open the valve to add water, and he should have included that in his explanation?

But I bet the experts here will tell that you should operate with the valve always open!

But good luck!

p.s. I know there are other threads on this forum that have discussed operating with the makeup valve, open or closed.