Some Rads heating at bottom only

quazzy

Hi all,

I have 3 rads that are only warm at the bottom of the units. Middle and Tops are cold.

All 3 affected rads are upstairs and there is another 3 rads upstairs that are perfectly fine.
All downstairs rads are perfectly fine too.

House was build in late 90s. Semi D. Gas Boiler. Vokera mynute 14-48 se.
Pressure reading is ~ 0.5 bar (not 1005 Certain - but as far as I can tell its always been like that and the rads were grand).
Gas Boiler is in utility room at ground floor. Hot Water Tank is in Hot press upstairs. There's a Tank in the attic too.

I've bleed the rads and only get air - no water. So my assumption is that there is not enough water in the rads (not filling). Or perhaps it is a pressure issue?

In researching the problem I found this thread and it mentions open vented or sealed systems and the options to add more water into the system but I'm not sure exactly which is my setup is - any guidance would be appreciated.

https://www.boards.ie/vbulletin/showthread.php?p=70716798

John.G

If the pressure gauge is located near a red expansion vessel on the ground floor near the boiler then 0.5 bar is a bit marginal to overcome the static head to reach the upstairs rads, you might see a stainless braided hose near the pressure gauge with valves at either end, you can then top up the system, ideally ~ to 1.0 bar when cold or if system is hot just increase the hot pressure by 0.25/0.5 bar and recheck when system has cooled down. You may have a semi sealed system but just see if you have the system I described above, first.

Just give the base (not the face) of the pressure gauge a tap with a spanner or whatever first in case gauge is stuck.

quazzy

John.G wrote: »

If the pressure gauge is located near a red expansion vessel on the ground floor near the boiler then 0.5 bar is a bit marginal to overcome the static head to reach the upstairs rads, you might see a stainless braided hose near the pressure gauge with valves at either end, you can then top up the system, ideally ~ to 1.0 bar when cold or if system is hot just increase the hot pressure by 0.25/0.5 bar and recheck when system has cooled down. You may have a semi sealed system but just see if you have the system I described above, first.

Just give the base (not the face) of the pressure gauge a tap with a spanner or whatever first in case gauge is stuck.

Pressure Gauge is a dial on the Boiler Unit. And there is no expansion vessel beside the boiler on ground floor or in hot press. Could it be in attic?

John.G

That looks like a system gas boiler in which case the exp.vessel will be integral within the boiler casing.....the topping up hose will be located somewhere near a mains supply, maybe the hot press or under/near the boiler.

quazzy

Thanks for the reply.

There is definitely no topping up hose at boiler.

Here is a few pics of hot press.

John.G

Does the pressure rise when the system heats up???.

It's possible that you have a semi sealed system, you would/should have a small feed and expansion tank in your attic with a non return valve, when the system is cold, then the system pressure will be equivalent to the static head from the tank water level to the boiler, when the system heats up the non return valve closes and the pressure should rise by ~ 0.5 to 1.0 bar and then return to 0.5 bar on system cool down. If the pressure remains constant then either there is no non return valve in the system or its stuck open.
Also I have read posts that referred to short cuts being (wrongly) taken where the cold water storage tank (CWST) in the attic is used as the supply.
I am still a bit surprised that it hasn't a top up loop as 0.5 bar is borderline as well for resetting/tripping the boiler pressure switch which is generally fitted to this type of boiler.

Again, if the tank in the attic is supplying the make up water then it should be OK to ensure the upstairs rads are full of water after venting.

quazzy

John.G wrote: »

Does the pressure rise when the system heats up???.

.

I'd have to check this. Thanks for replies so far.

I'll take a trip up to the attic to and see what else I can figure out

John.G

FYI, a typical filling loop, attached.

quazzy

Based on your pics I don't have filling loop in hot press or at boiler.

Didn't get up to attic today. Might try tomorrow or Wednesday. Will post back findings.

John.G

Also check if pressure rises with temperature increase.

Your third pict in post #5 shows a chromium pipe to the left at the back, is that connected to anything or is it just a bar that was thrown into the back?.

quazzy

Boiler Update: When Boiler is off pressure is zero. Once I turn it on it only makes it to 0.5 bar - seems to stay there until unit is off again.

Attic Update: I went up last night and found all ( i think) cooper pipes from hotpress - they dissappear under insulation and them (I assume) appear again insulated leading up to water storage tank.

Metal Bar Update: Its not related to the plumbing, its only some old piece of something.

Images attached.

John.G

OK then I assume you have a Hot water cylinder somewhere?, if the boiler make up is fed from one of those storage tanks then its more than likely that the make up pipe will tie into the hot water cylinder coil loop, generally the lower of the two pipes going into the cylinder, so have a look at this and post a pic.

quazzy

Hot Water Cylinder is in the Hot press.

These 3 pipes are the only thing I have at my disposal.

https://www.boards.ie/vbulletin/attachment.php?attachmentid=497725&d=1576501170

The middle one marked Heat ( I assume) is the feed from the attic water storage into the heating systems. Copper pipe is smaller than the 2 either side of it. I'm pretty sure those 2 are for turning off the water to taps etc...

So, do I assume that the middle tap would control the amount of water in the heating system and opening it for a few seconds will fill the heating system with a bit more water from the Attic tank and maybe increase the water pressure?

quazzy

one more update and picture.

This pic is where the pipes lead to and join the cylinder

John.G

Yes, that looks like a 1/2 ins pipe so ensure that someone is watching the boiler pressure and crack that valve open and shut it if the pressure > 0.5 bar just in case its mains pressure.

quazzy

John.G wrote: »

Yes, that looks like a 1/2 ins pipe so ensure that someone is watching the boiler pressure and crack that valve open and shut it if the pressure > 0.5 bar just in case its mains pressure.

Cheers.

I'll give it a try once I have someone else to check the pressure.

Silly question, but can this be opened while boiler is running or just when switched off?

John.G

IF its a mains supply then ideally the boiler should be pressurised to 1.0 bar when cold/off but even if running you can bring it up by say 0.3 ish until the boiler is off/cooled down, if its a tank supply you can just open it, period. the way this system is normally set up is that there is a non return valve in this (tank) pipe so the boiler when cold might read 0.3/0.5 bar but when it heats up the NRV will close and the pressure will build up to 1.0/1.5 bar but will return again to the cold setting each time the boiler cools down.
IF there is no NRV and you let the isol v/v open then the pressure will not change appreciably but if you shut it when boiler is cool then the pressure should build up as above when hot ~ 1.0/1.5 bar.

quazzy

Been a while since I last posted on this but here is the update.

I couldn't figure out the problem so I ignored it and set up a temporary workaround (portable electric radiators) to give me more time to ponder. Winter passed and the days grew warmer and so I had more time to play with until the next Autumn / Winter arrived.

Anyway, I found ANOTHER pipe with a red tap in the hot press ( 2 feet to the left of the ones attached below)
https://www.boards.ie/vbulletin/attachment.php?attachmentid=497725&d=1576501170

No idea why I hadn't seen it before, I think I was so focused on that side of the hot press I missed the other one completely.

Anyway, I gave it a turn and heard some water flowing. I closed it off and went to check the boiler. Pressure went back into BLUE zone (~1.0 Bar) and the problematic radiators are now full of water and heating.

I had to repeat the process a few times. Bleed Rad, Add more water to System etc... but it seems to be working now.

Hurray.

One minor issue is the red tap that lets the water into the heating system has a tiny leak (1 drop every 2 minutes give or take).
Again, my approach here is ignore it now, add a workaround (Towel) and wait for inspiration.

Thanks for all the posts and help to date. You were right all along - I just couldn't see the bleedin' pipe