No Water in Radiator When Bleeding?
It's absolutely normal to get a small trickle of water when you're bleeding a radiator - and a sign that you've dispersed any trapped air. But what if is no water when bleeding the radiator?
When you bleed a radiator and don't see any water at all, there are several potential causes, and it's best to troubleshoot to work out whether there's a bigger issue at hand than an air bubble or two.
Usually, a lack of water in radiators on upper floors is a sign of low circulation pressure, which can be as simple as resetting the pressure on your boiler or might mean that you have a failing pump or an expansion tank that isn't large enough.
Here we'll look at several underlying causes for lack of water in a radiator and what to look out for.
Reasons There May Be No Water in the Radiator When Bleeding
As we've mentioned, one possibility is that your upper floor circulation isn't working correctly - so the system doesn't have the pressure required to force heated water upstairs.
This scenario is more likely if your boiler is downstairs or you have an older central heating system, so it might be necessary to call out a plumber if repressurising the system doesn't make any difference.
Purging any air bubbles is also one way to resolve this problem if you have a pressure balance.
Still, it's important to take safety precautions since there is a risk of scalding water being suddenly released.
Another alternative might be that you have an airlock, which you can usually fix by:
- Turning off all of the radiators apart from the one that has no water - if all your radiators have the same issue, you'll need to work on them one at a time.
- Turn on your central heating to force the water to go to the one radiator.
- Bleed the radiator to try and remove any excess air, and then move onto the next.
This task is best performed with the boiler turned down to a low heat setting, as you need the pump to be running but should minimise the hazard of boiling water.
If that doesn't work, you may need a plumber to flush the system for you - and it might be a question of replacing pipework or radiators if you have a build-up of sludge in an older system.
Troubleshooting Radiators With No Water
Radiators that aren't warming up are a typical central heating problem, so bleeding the radiator is the first port of call since it's commonly a case of removing trapped air from the system that is blocking warmed water from filling the radiator.
Stuck Pins in a Radiator Thermostatic Valve
If your radiator is still cold after bleeding, or you don't see any water coming out of the radiator valve, it's time to work through potential causes methodically and try to pinpoint the reason.
- Check your radiator valve - if you have thermostatic valves (or TRVs), the pin can become stuck. The TRV will be the larger of the two valves on your radiator, with temperature control numbers for you to turn the heating up or down.
- Unscrew the cap, and you'll see the pin - if this is stuck in the 'shut' position, it prevents water from flowing into the radiator.
- Loosen the stuck pin with an adjustable spanner or a grip, and gently grab the pin and wiggle it up and down. This movement should free the pin, and you'll feel a little slack, which means the problem is solved.
- Turn the central heating back on - and fingers crossed your radiator will fill with water and begin to warm up!
Flushing Air Locks From a Radiator
We looked at airlocks earlier, so it's best to flush the radiator out if the pin doesn't seem to be the problem.
If you don't have any plumbing experience or aren't confident, this might be the stage at which you opt to call a plumber.
The key to flushing out an airlock is to try and disperse pressure in the radiator, so if isolating one radiator at a time hasn't worked, you can remove the whole air bleed system and add a connection that you'd use for a garden hose.
If you turn off the heating and connect the hose into a large container (or leading out of the window), you can open the thermostatic radiator valve and see a surge of water coming out of the hosepipe.
Hopefully, this pressure should clear your airlock and get your radiator back in good working order.
Balancing a Heating System
Another possible cause is that the water flowing around your central heating system isn't even, in which case you'll need to balance this out.
Balance means that the water flowing from your boiler and pump goes into each radiator evenly, rather than skipping some rooms or one floor of your house.
At the end of your heating system, the radiator furthest away from your boiler is usually the unit that won't work properly if you have an unbalanced flow of hot water.
- First, bleed your radiators, especially if you have cold spots.
- Turn off the central heating, allow the radiators to cool, and then list each unit in your home.
- Open both radiator valves on each radiator, all the way, turning the valve anti-clockwise.
- Check which radiator heats the fastest, and note the order in which your radiators warm.
- Turn the heating off again, leave the radiators to cool completely, and then switch it on again - it makes sense when you reach the final step!
- Close the valve on your fastest heating radiator, and then reopen it just by around a quarter of a turn.
This process should rebalance your radiators!
Replacing Radiator Thermostatic Valves
Radiators that stay cold, even if the heating system is on and you can't find any other fault, may have a faulty valve that you'll need to replace.
It's advisable to check first whether it's a stuck pin, as these sometimes get stuck in an 'off' position, which needs a quick wiggle to release the pin and allow the water to flow.
However, valves can break down, and older radiators may well have degraded thermostatic valves, especially if they're used often.
Valve pins can rust, break, get jammed in place, or wear down.
Replacing the valve will solve the problem of a cold radiator and mean that you won't need to replace the whole radiator unit.
Chemical Inhibitors in Heating Systems
Finally, if you call out a plumber to try and diagnose the issue with your central heating, they'll check the inhibitor levels as a standard check.
This factor is often overlooked, but in essence, the water in a heating system can, over time, react with internal metal components. The process results in corrosion, with tiny metal flakes getting caught up in your pipework and radiators.
Particles restrict water flow and build up into a sludge that lines the bottom of your radiators.
The boiler and pump have to work much harder to force water through the system, and a long-term sludge build-up can cause a boiler to fail.
Chemical inhibitors are additives used in a central heating system to prevent corrosion and can extend the life cycle of your heating appliances and radiators by many years.
Suppose you have an older central heating system and have repeated issues with sludge. In that case, it may mean that some units need replacing - so a chemical inhibitor is a preventative measure to avoid any major maintenance issues arising.
Frequently Asked Questions - No Water in Radiator When Bleeding?
Let's answer some of the most frequently asked questions about why there may not be any water in your radiator when bleeding.
What Does it Mean if I Bleed a Radiator and Get Water Right Away?
If you're bleeding a radiator and get a gush of water without any hissing noises, it's a good thing! That means your radiator doesn't have any trapped air.
Should there be lots of hissing, then you'll need to keep the valve open until all the air has escaped, followed by a little water.
Is No Water When Bleeding a Radiator a Bad Thing?
Potentially, yes. If you don't have any water coming out of a radiator after bleeding, it means you could have something blocking the bleeder valve, the pressure is insufficient in your central heating system, or it could be something different.
Ultimately, if you can't find an easy solution, it's best to call a professional plumber to identify the problem.
Should Water Escape When Bleeding a Radiator?
It should, yes, you'll usually get some drips of water when you first open a radiator valve, and then the hiss of air bubbles escaping.
You should avoid opening the vale all the way (unless you're flushing an airlock following the steps above).
That's because if you open the valve all the way, you'll get a significant volume of water, which could be dangerously hot if you haven't turned off the heating and waited for your radiators to cool first.
References:
- https://www.traderadiators.com/blog/radiator-cold-after-bleeding
- https://www.reddit.com/r/HomeImprovement/comments/djajci/bleeding_radiators_some_have_hissing_and_no_water/
- https://www.diydoctor.org.uk/projects/radiatorproblems.htm
- https://www.bestheating.com/info/faqs/should-water-come-out-when-bleeding-a-radiator/
- https://www.askaboutmoney.com/threads/radiator-wont-bleed.68736/
- https://diy.stackexchange.com/questions/10092/why-isnt-water-coming-out-of-a-radiator-in-my-freshly-pressurized-system
- https://www.brownstoner.com/forum/#!/general-discussion:bleeding-radiators-no-water
By Johnny Fuller
Home Improvement editor at NWrenovations.com