Radiators not heating upstairs? It’s usually flow, not “mystery air”.
This is one of those problems that makes people feel like they’re going mad. Downstairs is toasty, upstairs feels like you left the windows open… and the boiler is sat there acting innocent. A lot of customers land here after searching “boiler repairs near me” because it feels like the system is failing.
Most of the time, the boiler is producing heat fine — it’s the distribution that’s off: balancing, restricted circulation, sludge in the wrong place, pressure issues, or a pump that isn’t shifting water properly. This page helps you spot the pattern and choose the right fix without turning it into a bigger job.
A Newham pattern we see a lot (especially in terraces)
There’s a type of call we get in Newham that’s almost predictable: “Downstairs rads are fine, upstairs are barely lukewarm.” You walk in and the hallway radiator is roasting, the living room is comfortable… then you go up the stairs and it’s like a different house.
Nine times out of ten the property has had changes over the years — an extra radiator added in a loft room, pipework rerouted at some point, maybe even a mix of old and newer radiators. The system still “works”… it just doesn’t push heat evenly anymore.
It’s not glamorous, but it’s solvable. You just need the right diagnosis before you start draining things or chasing random fixes.
Why upstairs radiators suffer first
Hot water takes the easiest route. If downstairs radiators have open valves and the system is unbalanced, they’ll “drink” most of the flow. Upstairs, being further away (and sometimes higher resistance), gets the leftovers. Add any restriction — sludge, a partially closed valve, a tired pump — and upstairs is the first place that shows it.
Common causes (in order of reality)
- Balancing: downstairs valves too open, upstairs starved of flow.
- Sludge/restriction: system contamination reducing circulation to “furthest” rads.
- Low pressure / poor fill: flow drops, air pockets form, upstairs struggles.
- Pump or filter issues: pump weak or system filter blocked.
- Valve problems: stuck TRVs or lockshields, often upstairs where they’re rarely touched.
What it usually isn’t
It’s not normally “just air” if the same pattern keeps coming back. Bleeding can help temporarily, but if the system keeps losing performance, there’s a root cause underneath.
Also, don’t assume it’s automatically a boiler replacement thing. These are often fixable circulation problems.
Safe checks you can do today (without making it worse)
- Compare radiator temperatures: Pick one hot downstairs radiator and one cold-ish upstairs radiator. If the downstairs one heats fast and the upstairs barely changes, that’s a flow distribution clue.
- Check all TRVs upstairs are actually open: Sounds basic, but it catches people out — especially on guest rooms where TRVs get turned down and forgotten.
- Bleed once, don’t obsess: If you get a lot of air from multiple upstairs radiators, note it — but don’t keep doing it daily.
- Look at pressure behaviour: If pressure drops over time, don’t just keep refilling. That’s how “simple heating issue” becomes “book a boiler repair”.
- Don’t drain the system to “see what happens”: Introducing oxygen can increase corrosion and sludge over time.
If you want a fast steer from someone who does this daily, call: 07727 154746. It’s the same number people ring after searching “gas boiler repair near me” — we’ll tell you if it sounds like balancing, sludge, or a bigger circulation fault.
Stop DIY block (don’t cross the safety line)
Adjusting radiator valves is one thing. Opening a boiler case, messing with gas components, or pushing the system while it’s misbehaving is another. If you’re unsure, it’s always cheaper to ask than to “accidentally create a second problem”.
When it’s balancing… and when it’s something you should book in
If the system has simply drifted out of balance, you can often improve it by restricting flow to the hottest downstairs radiators (slightly closing lockshields) so water is forced to travel further. Done properly, it’s a tidy fix.
If you’ve got cold spots, slow warm-up, or multiple radiators acting odd, you’re likely dealing with restricted circulation. That’s where we stop guessing and do proper diagnostic work — because “upstairs rads cold” can be the visible symptom of a wider issue.
If you want the clean, transactional route (and you’re basically at the “boiler repair” stage), book it here: boiler repair in East London with proper fault-finding.
Or if you want to understand exactly what we check first: what our boiler repairs visit covers.
If you’re in Newham and the upstairs bedrooms stay cold while downstairs is fine, it’s usually a flow problem in the system — not “bad luck”. If you’re stuck near Stratford after work and you want someone to tell you straight what it sounds like, call 07727 154746.
Related diagnostics (same intent, no cannibalisation)
If your upstairs radiator issue comes with other symptoms, these are the three sibling guides that pair with it:
- Radiator cold at the bottom (sludge signs)
- Boiler losing pressure (common causes)
- Kettling boiler noise causes (scale vs sludge)
Want to route this fast from the main site? Back to ARA Services homepage.
FAQs
Why are upstairs radiators colder than downstairs?
Usually because of flow distribution: the downstairs radiators take most of the circulation if the system is unbalanced. Any restriction (sludge, valves, weak pump, low pressure) makes the “furthest” radiators suffer first.
Will bleeding radiators fix the upstairs problem?
Bleeding can help if trapped air is the main issue, but if the same pattern comes back repeatedly, it’s normally a symptom of something else (balancing, pressure behaviour, or restricted circulation).
Is this a boiler fault or a radiator fault?
Often it’s neither in isolation — it’s the system as a whole. The boiler might be producing heat fine, but the system isn’t delivering it upstairs. That’s why proper diagnostics beats guesswork.
What’s the quickest sign it’s a balancing issue?
If downstairs radiators are consistently very hot and fast, while upstairs stays lukewarm, that’s a classic unbalanced system signal. It’s even more obvious when one downstairs radiator is “too hot” compared to the rest.
When should I call someone instead of trying more DIY?
If the boiler locks out, pressure keeps dropping, or you’re repeatedly topping up and bleeding without lasting improvement — call. That’s when a straightforward heating issue can turn into a boiler repair job.