How do I bring the pressure on my boiler back up?

Submitted by chunderilla t3_yys8t1 in DIY

New homeowner here. I have no idea how any of this is supposed to work, but our radiators were “peeing” (they gurgle) as my daughter puts it, because of air in them. I’ve bled them and obviously the pressure in the boiler has now dropped. We have a Viessman 333-F if it helps and I don’t really know if I need to fill the thing with regular tap water or get some special type of fluid that goes into the heating circuit.

Currently, the pressure gauge is basically just above 0, which isn’t ideal.

Here’s where I think it needs to be filled

https://i.imgur.com/byFViCK.jpg

The pipes with the blue thing is connected to the radiator as shown in the previous photo

https://i.imgur.com/jMk7x6m.jpg

https://i.imgur.com/yVXZTY6.jpg

I’m not sure if that’s how I fill it or if that’s just the hot water going up to our kitchen.

Any help would be appreciated!

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Comments

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VikingsGoneWild t1_iwvyb6w wrote

Call a pro. Boilers are not something to play around with.

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chunderilla OP t1_iwvz3k8 wrote

We did. It’s a 2 month wait for us because of a shortage in workforce but a crazy amount of work.

According to my quick google searches, apparently this can be done by yourself so I thought I’d give it a go haha.

Question: if we have a low boiler pressure does that affect the heating in the house or will we be freezing for 2 months?

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VikingsGoneWild t1_iwwinrm wrote

Dude I would not attempt to try this yourself. I do this shit for a living and boilers can be very dangerous when messed with improperly. That and or you can damage the boiler itself. Not everything is DIY. While the labor shortage is real after hours/emergency calls are still a thing. While costly it’s not nearly as costly as a new boiler.

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Ni987 t1_iww2nk3 wrote

It’s not rocket science.

Low pressure will prevent proper circulation e.g. you will freeze your ass off.

You need to figure out where there is a connection you can hook the water hose up to?

Once connected the process is as follows:

  1. Turn of furnace.
  2. Open tap water
  3. Open valve on heating system
  4. Monitor pressure - don’t overfill it
  5. Shut off valve
  6. Shut off tap water
  7. Turn on furnace.

A few details. Important you follow the order of opening tap water and heating valve as described or you might push water from the heating system into you tap water supply. Don’t contaminate it - so follow the order described.

Do not not overfill… you have a safety release valve which will vent over pressure (looks to be the blue valve on your picture). However … they are rarely used, so once they open? They might not fully close again. Which means they will keep leaking until replaced. So don’t push it.

Hot water expands. Once the cold water you filled into the system heats up? It will expand and increase pressure slightly. So don’t fill it to the max pressure. Once the water heats? It might trigger the safety valve.

In conclusion. Not rocket science. It’s something every homeowners should be able to do on a yearly basis.

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samtresler t1_iwwgtuu wrote

Gosh, and here I thought pressure reducing valves were a thing.

Don't think you should monkey around with hoses for this.

P.s. Don't follow this advice.

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thexsunshine t1_iwvyrtk wrote

This, you can accidentally hurt yourself very easily

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jeffersonairmattress t1_iww34z5 wrote

Boilers should fill automatically with makeup water. You do not fill them by other means.

Read the boiler manual- if you bled the rads, did you just open bleed valves at each one until there was no air? Or did you see water pouring out, it slowed down and then stopped, indicating zero pressure? If the latter, the boiler may have sensed a leak/low pressure and shut down so you have to restart it- it may have closed a solenoid that shuts off the line to the front-mounted gauge on the boiler. Did you lock out or shut off the boiler when you did this? There should be an automatic spirotop-type bleeder and you shouldn't need to do this at all; there is almost certainly one in the boiler- Viessmann boilers tend to accomplish every feature within them. But these things can get deposits in their vent and become blocked- a plumber needs to tend to that. Don't monkey with a fancypants boiler like this.

The grey hose and corrugated line all leads to drain- that's where excess pressure/condensate, etc. goes. You have 7 bar of pressure in the supply lines- did you close that angle stop handwheel when bleeding the rads and forget to open it?

Some gauges are not reading all the time and need to have a valve before them opened to read pressure. Does this boiler heat your tap water via a pump and heat exchanger in another tank and also feed your radiators? are you sure there are no other lines coming out of the boiler?

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chunderilla OP t1_iwy6nlt wrote

I released air from the bleed valves until some water showed up. There’s still some air in the system but I cannot bleed the rest of it out because I’m assuming that the water level is too low.

I think I’ll wait for a tech to come round at some point. I’ll figure it out from there!

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Winjin t1_iww8ns1 wrote

Weird, how hard can it be? All the Baxies and other boilers here in Caucasus have instructions for them and easy access to add some tap water to the circulation. Can you find the manual online? I suggest just finding one and reading it.

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Ni987 t1_iww19pi wrote

Pressure gauge on the second photo shows 5+ bars?

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ChiefMedicalOfficer t1_iww345c wrote

Mains water probably.

Gauge on the boiler itself looks very low.

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Ni987 t1_iww5j0k wrote

You are right - second picture shows it’s connected to the water tap.

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drgreenway t1_iww2xtk wrote

I can't tell from your photos which pipe is which. What's the angled tap valve for on the wall? Is that the water mains inlet valve? It'll need filling under pressure, there will either be a valve which is already connected which needs opening, or a bridging tube which needs connecting first.

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drgreenway t1_iww3ev2 wrote

The more I look at it, the more I think you should open that valve. I spotted that it is connected to the mains, I didn't see the tap on the wall before.

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ChiefMedicalOfficer t1_iww3efu wrote

Definitely try and get someone in to have a look BUT as it looks like that's an issue itself is there an access door or hatch to the boiler? This won't be a hatch that has to be unscrewed, just a simple door or panel that can be pulled open.

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get-r-done-idaho t1_iww6vjn wrote

Do you have softened water? Hard water will build scale in the unit. You will need the normal operating presser and make sure to leave room for expansion. I normally work with steam boilers but they are similar. It would be best to get a professional.

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chunderilla OP t1_iwwbfb1 wrote

Yeah this is my biggest concern right now with just using tap water because we have pretty hard water. We had a company redo all of the radiators in the house this summer and they said that they bled the entire system and refilled it, but I wasn’t around for all of that and I wish I knew what they did because I have no idea how they did it or if they brought their own water for the system.

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jef612 t1_iww85sk wrote

Just stop. Honestly you can do some pretty good damage to your system if you don't know what you are doing. You have a nice boiler there - someone in your area will be able to look at in the next week. Don't buy the labour shortage crap - keep calling until you find someone qualified to look at your system.

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Once the tech is on site - ask him to spend a few minutes with you showing you where you can add water to the system and what else you can monitor/maintain as a homeowner.

​

Boiler systems are sealed, and if you are continually adding water then it has a leak somewhere that needs to be addressed. Adding small amounts of makeup water is OK, however adding water over time without addressing the leak will cause much bigger problems over time. Don't buy the labour shortage story - keep calling around.

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chunderilla OP t1_iwwcb0r wrote

I think the issue is that we just renewed all the radiators this summer so there must’ve been some trapped air in the system which is why the pressure’s dropped since I’ve bled some of the radiators.

Unfortunately, the labor shortage is a thing where we live right now. Even my neighbours have been complaining about the waiting lists they’re on or the ridiculous amounts of money you need to be willing to fork out just to make it worthwhile.

I think I will wait and see if either a professional can come by or if someone we know knows how this stuff works can guide me. Last thing I want to do is have to wait 6 months for a new boiler to be delivered and installed just as winter’s coming round

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jef612 t1_iwwg8ad wrote

https://viessmanndirect.co.uk/files//cf26e1c5-3b9f-43ed-980e-a31c00abe9a2/WS3C%20333-F%20Installation%20Service.pdf

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Page 8 shows you the fill valve. You would have to trace from there to see where it is connected.

air locks can be tricky - you may still need a tech there

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chunderilla OP t1_iwy69fn wrote

Yeah I just read that and thought exactly the same! Thanks for the link!

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Nuker-79 t1_iwwe91q wrote

Usually there is a panel on the boiler that opens up/pulls away and there will be two pipes joined together by means of a hose/pipe, this will usually have two valves or taps on it.

Remove power to the boiler first.

If you turn both these valves/taps to the open position, it will fill the water in the heating system. The system will have a pressure meter and will have a desired region, usually between 1&2 if I recall, usually also in green. Fill the system until the needle is in this region.

Once filled, turn off both valves and turn power back on.

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frzn_dad t1_iwxabyc wrote

I love how different this is depending on where you live. Have topped off a bunch of different boilers in the US never had to open a panel to find the fill valve. Always commercial boilers or single family homes in a high heating load area.

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