[Solved] No Hot Water from 35L Boiler After 1-Month Shutdown: Reasons & Solutions for 1.5-Year-Old System

Hello, I have a 35l boiler. It was constantly in use, there were no problems. Leaving the house for a month, I turned it off and turned off all the valves. After returning, I turned on everything as it was before, but I have no hot water in the tap, and the boiler is on. What could be the reason? I will add that the water installation is about 1.5 years old.

Maybe one of the valves has broken and does not work?

Check the safety valve to see if it is clogged.

When I open the safety valve, the water runs for a moment, a few seconds, and then stops.
No valve broke, it was disconnected from the power supply for a month, nothing else was done with it

So you already have a clogged safety valve in front of you. Or there was a vacuum.

The valve is on cold water. The cold water hose works fine, I checked it. The boiler took cold water normally and warmed up.

Maybe the boiler is not completely full of water? Turn on the cold water supply, open the nearest hot water tap and see if after some time air has escaped and water starts to flow.

I wrote about negative pressure.

@ Witold5 Yes, of course, but you only stated the fact that my colleague, the author of the topic, wanted to know what to do with it, so I just explained it to him. No offense.

I thought that having a boiler at home, the owner knew how to operate it. So I just hinted at the possibility. And these are just the laws of physics.

So what am I supposed to do? Because I'm completely green in this topic .. I've already done what Markutek recommended, but nothing happened

Do what we advise.

markutek87 wrote:

Turn on the cold water supply, open the nearest hot water tap and see if after some time air has escaped and water starts to flow.

From there, start and write what effect.

There is no effect whatsoever. It was supposed to be here, excuse me, the dictionary on the phone ... The post has been improved, as you can see

That is, you should read what you wrote.

And write whether warm or cold water is flowing from the warm tap, or only the air itself hisses? Wait, from the boiler, if you don't have pressure, you haven't unscrewed the valve or the diaphragm that gives the pressure is broken. And how long does it take cold water to heat up? Can it fly from the safety valve when water is being tapped?
I have no knowledge, but when I see a diagram of a typical boiler, we will see if it is the fault of the hot water outlet being blocked or the diaphragm rupture.
EDIT is this effect cold water or air?

The author of the topic writes that the installation is 1.5 years old, so I would rather not suspect mechanical damage.
How do you know there is hot water in the boiler? If you are not sure that the water in the boiler is there, do not turn it on.
Before you turn on the boiler, you must first turn on the water.

Do you have one hot water outlet? The battery may be clogged.

Maybe a stupid question: did you open all the valves supplying cold water to the boiler? Main for an apartment / house, separate for a bathroom? The "new" water flows into the boiler, or is it just "old"?

So yes: there was water in the boiler, because I drained it all, and then I refilled it. The boiler is 35l, filled up quickly, less than 5 minutes. I turned it on, the water heats up because I drained it a bit again to check it and it was flying warm. I unscrewed all the valves, I even tried to unscrew the faucet in the kitchen, the hot water pipes are empty. The water is standing in the boiler

How did you come down, which way? Did you unscrew the pipes, hoses?
The battery is probably not, because there is no more water at the safety valve and you have to look for it there.

Wait - where did you drain the water from the boiler? First it was cold to fill it completely, and then it was warm? Safety valve? Show a picture of these hoses under the boiler.

Since you physically unscrewed the battery and you did not have hot water, maybe one of the valves did not open physically, even though you turned the tap or moved the lever. A clogged pipe cannot be ruled out, but in such a new installation, if you have not made a revolution in the walls now (which could damage the pipes), disconnect the hot water hose coming from the boiler (maybe just loosen it), the point is that it would be known that this warm water is physically in it, and that no sediment has accumulated that is blocking the drain. Do this with the cold water supply closed and the boiler off. Be careful as the water can get really hot. PS The hot water hose has a different temperature than the cold one?

The author of the topic does not speak, so the topic has been solved.

Witold5 wrote:

The author of the topic does not speak

Sometimes you have to wait 3 days.

I figured it out a little more, unscrewed the safety valve, cleaned it, screwed it on and now the water is running normally, but the hot one is still not there

So now the section between the safety valve and the battery.

Witold5 wrote:

So now the section between the safety valve and the battery.

As I wrote, I think everything is fine with the safety valve, because it works as it should, the battery is also functional, I also checked it, i.e. I screwed in a different one and it did not change.
I unscrewed the hot water hose from the boiler, a lot of air escaped at first, and nothing else. Not a drop of warm water. Rather, there is a problem, but I don't know how to solve it. There is one more point. The apartment was not heated in my absence and the temperature was quite low. Could this have had any effect? I will note that the water at the main riser was turned off, and I drained the water from the pipes

Air in the boiler for me. There is still air in the boiler, possibly in the pipes too. Turn on the cold water supply to the boiler, unscrew the hose from the hot water outlet and wait. Not only 5-10 seconds, but only 5-10 minutes. Do not connect the heater.
Cold water will flow into the boiler, it will force the air out, and water will flow from the hose on the hot side. Cold water flows from the tap normally? How do you turn on the tap, it does not shoot / spray?

markutek87 wrote:

Air in the boiler for me. There is still air in the boiler, possibly in the pipes too. Turn on the cold water supply to the boiler, unscrew the hose from the hot water outlet and wait. Not only 5-10 seconds, but only 5-10 minutes. Do not connect the heater.
Cold water will flow into the boiler, it will force the air out, and water will flow from the hose on the hot side. Cold water flows from the tap normally? How do you turn on the tap, it does not shoot / spray?

Cold tap water runs normally, and if there is water in the boiler, should I drain it and then refill it to push the air out?