Hydronic heating system problem - need answer fast

I have left a message with a recommended heating repair company, but while I’m waiting, please assuage my concerns.

We have a hydronic (hot water in the floors) heating system combined with an on-demand hot water heater that is about 8 years old. Yesterday it started making this continuous high-pitched tone; sometimes the tone varies a bit in pitch or intensity, but it’s pretty steady. It goes away for a while if I turn the system off and when I turn the system back on it takes a while to come back (I don’t know how long, at least an hour).

The backflow valve is inspected every year by city ordinance; other than that, it has had no attention since being installed.

My question is: is this noise a prelude to explosion or other disaster, or can I leave the system on until I hear from the heating company?

Does the sound seem to be associated with water flow? That is, does it start, stop, or change when you turn on the hot water somewhere? Does the water heater have controls that have a display or LEDs that might show an error code? Is the heater gas or electric?

I have hot-water baseboard heat, and when I get odd tones, it’s time to lubricate the water pump and motor bearings. You might look for little oil cups on your pump, and put in a couple drops of motor oil.

First, the sound stopped about 30 minutes after I left a message for the heating repair place. Who, incidentally, still haven’t called me back. Before that point, it had been going on for more than a day (discovered Saturday night, continuing on Sunday until Monday morning).

There are no error messages showing. The system is powered by natural gas. The noise was pretty steady most of the time, I couldn’t tell if any variations were caused by hot water use.

The system is a tall box with control dials and numerical readouts on the front. I don’t see any place for owner servicing. I’m happy to pay for a professional to take a look at it if I can get one to respond. I don’t know what it is with businesses these days who don’t want my money. I thought I was quite clear and polite in my message. If they don’t service this kind of thing (I was referred to them by my plumber) the least they could do is call me back and tell me, and for a bonus they could maybe refer me to someone who does.

I appreciate the idea that something needs to be lubricated. The noise itself did not sound like squeaking, more of a steady tone, but I also admit pure ignorance when it comes to things like this. For the “how stupid are you?” thread, I let the contractor install this system 8 years ago and never asked him for a reference to someone who would do service.

At first, I was wondering why anyone would be concerned about problems with their heating this time of year.

Then, I looked at your location.

“The coldest winter I ever spent was a summer in…”

The same box heats all the water for the house too.

Could have been air in system. There should be a float valve on the pipes near the burner, if you’re lucky it was nothing but air escaping.

If you can’t get anyone to respond, call the gas company. They should take possible safety issues seriously. But you might want to check to see if they provide services or not, otherwise they might simply shut off the gas until you repair it. Not the best solution, but one you should be aware of if you can’t get a heating company to respond.

I finally found someone to come out and take a look. The noise is coming from a broken* three-way valve, something to do with whether the boiler is working on heating water for the hydronic heating system or for hot water use (obviously I don’t understand exactly how all this works). And not surprising on an 8-year-old system that’s never been looked at since installation, there is other work to do. The heat exchanger needs cleaning, and the condensate trap is broken and leaking. So we’ll get all that fixed, and I’ll be out some money, but now I have someone who can come and check it once a year.

*The valve is broken in that it is making this noise, the technician did not seem to be worried about actual failure of the valve to do its job.

So it’s the mixer. It mixes cold water with hot so you don’t get scalded by hot water from your faucets. I’d say it should have lasted longer than 8 years but recently I’ve found boiler parts ain’t what they used to be.

I don’t think it’s the mixer, that’s not the way he described it, but I can ask again. I think the mixer would be out where the manifold is, not right in the boiler.

I think the item being described is a zone valve. Your system has at least two functions. One is to heat domestic water, the other is your heating system. The actual boiler does care why it’s being called on, it just makes hot water. The zone valve(s) control where the water goes. Zone vales are electro-mechanical and they wear out over time.

That’s my guess.

A zone valve makes sense for that purpose. Sounds like there would be a secondary hot water tank on it’s own zone.