Hot flow and return pipes, hot upstairs rad but cold rads downstairs

[Mark Garland]

As in the title, the flow and return pipes both get hot when the heating is turned on, yet only the upstairs radiators get hot.

I am very puzzled by this. Even turning off all thermostatic valves upstairs, none of the downstairs rads get hot. Our plumber says there must be a blockage looking for a second opinion. Not sure how there can be a blockage if the return is still hot.

Any help would be appreciated.

Mark

 

[ShaunCorbs]

get Vaillant out there have a decent set of lads

 

[Harvest Fields]

No worries, it's just the boiler has a warranty but I don't want our plumber to try and go around it by blaming the problem on our pipes.
We haven't got much experience with them so still building up trust so don't want to be given the run around hence asking on here.

Your first point of call should always be your gas engineer. But if you have lost faith then go straight to Vaillant. They are generally really helpful and if you have warranty they will come out and have a look.

 

[Mark Garland]

could be pump stuck happens with the new eco pumps but need to be gas safe to have a look

Yeah I'm not going to go taking the pump apart! Seems odd though that the upstairs rads still get hot relatively quickly if the pump was stuck?

 

[Harvest Fields]

get Vaillant out there have a decent set of lads

Two great minds... well one anyway

 

[ShaunCorbs]

Hmm, I could time it, what time frame should it be?
May have underestimated it last time, time flies when you're having fun staring at a temperature guage

if it shoots up and doesnt go down within 2-3 mins and boiler doesnt stay lit (fired) then i would say pump could be stuck

 

[ShaunCorbs]

Yeah I'm not going to go taking the pump apart! Seems odd though that the upstairs rads still get hot relatively quickly if the pump was stuck?

heat rises

 

[Harvest Fields]

heat rises

Was just typing that as well.

 

[Mark Garland]

if it shoots up and doesnt go down within 2-3 mins and boiler doesnt stay lit (fired) then i would say pump could be stuck

Right, just tried again. After turning the thermostat up, temp rose very quickly to 57, then dropped back down to 50 (sounded like pump turned on), then was fluctuating from 55-50 after 1 minute.

After 3 minutes its 57

4 minutes its 59

5 mins its 62 (boiler still fired)
7 mins in its 66

So, does seem to be rising slowly.

I am heating a click sound every so often (every 10-30 seconds) not sure if that is important.

 

[ShaunCorbs]

i would say thats fine then

 

[Mark Garland]

heat rises

Yeah I get that but surely it cannot rise that fast? Or is it the hot water rises to the top of the circuit so kind of pushes itself round?

I will try our gas engineer first but failing that will give Vaillant a ring.

 

[Harvest Fields]

i would say thats fine then

The integral may need setting up properly

 

[Mark Garland]

One other thing, if the pump was stuck but the rads get hot upstairs because the hot water rises, why is the return pipe still piping hot?

 

[Harvest Fields]

One other thing, if the pump was stuck but the rads get hot upstairs because the hot water rises, why is the return pipe still piping hot?

The pump could be spinning but not on full rate. Modern pumps are supposed to modulate dependant on demand.

 

[ShaunCorbs]

so all your down stairs rads arnt working

 

[Mark Garland]

so all your down stairs rads arnt working

Correct, not a single one

 

[ShaunCorbs]

Correct, not a single one

if it was just one or two i could see maybe a blockage but not all of them, i would say boiler is at fault

 

[Mark Garland]

The pump could be spinning but not on full rate. Modern pumps are supposed to modulate dependant on demand.

I see, it still just seems strange how it cuts off at heating all radiators upstairs perfectly but none of the downstairs ones at all, they arent even luke warm. They are ice cold yet the return pipe to the boiler is super hot.

 

[Harvest Fields]

If your engineer cannot fix it, tell him you want him to book a warranty call from Vaillant.

 

[Harvest Fields]

I see, it still just seems strange how it cuts off at heating all radiators upstairs perfectly but none of the downstairs ones at all, they arent even luke warm. They are ice cold yet the return pipe to the boiler is super hot.

I cannot say any more. Really sorry mate. Your engineer should know what to look at on the boiler.

 

[Mark Garland]

If your engineer cannot fix it, tell him you want him to book a warranty call from Vaillant.

Will do.

I cannot say any more. Really sorry mate. Your engineer should know what to look at on the boiler.

No worries I appreciate your help on this anyway, I'll update what it was once we've had it looked at.

Thanks again

 

[Harvest Fields]

Will do.



No worries I appreciate your help on this anyway, I'll update what it was once we've had it looked at.

Thanks again

That would be awesome mate. It’s always nice to get some feedback. It’s easy to forget us once it’s been fixed. UNTIL NEXT TIME

 

[Mark Garland]

if it was just one or two i could see maybe a blockage but not all of them, i would say boiler is at fault

I am hoping that is the case, shelled out a lot of money for it and don't want to spend even more on additional work!

 

[Harvest Fields]

I am hoping that is the case, shelled out a lot of money for it and don't want to spend even more on additional work!

I would put money on it that it is diagnosed within 15 minutes

 

[ShaunCorbs]

I am hoping that is the case, shelled out a lot of money for it and don't want to spend even more on additional work!

easy way to tell if its blocked but requires removal of a rad

remove a rad and test if you have water coming out of each valve from the rad you removed if you have its not blocked

 

[Mark Garland]

That would be awesome mate. It’s always nice to get some feedback. It’s easy to forget us once it’s been fixed. UNTIL NEXT TIME

Too right, will definitely update as I know how frustrating it is when you find a forum post with your problem and the OP never actually updates with what the solution was!