Not enough hot water to go round!

[meispete]

I'm at my whits end with my heating system, as soon as I fix one problem another appears!

I have a Biasi condensing boiler, in charge of heating 9 radiators.

I have managed to balance the radiators to the extent where the house now heats up slowly but evenly.

The problem I have (or one of them at least) is that on many of the radiators the return valve is only open a quarter of a turn or so, and as such the bottom of the radiator only gets luke-warm at best.

If I open the return valve further the bottom of the radiator does heat up, but then another radiator at the end of the loop remains cold, almost like there isn't enough hot water to go round!

Is this down to the pump not being efficient enough, or something else?

The system doesnt appear sludged, whenever it's been drained down previously the water leaving is very clear, and all the radiators can fully heat up to the point of being untouchable top and bottom when the lock valve is opened (although other radiators then suffer).

Any ideas much appreciated!

Pete

 

[bengasman]

...If I open the return valve further the bottom of the radiator does heat up, but then another radiator at the end of the loop remains cold, almost like there isn't enough hot water to go round!

Sounds like it is only a matter of balancing.
Keep going round ( with breaks to stabilise ) and open ls valves little by little until all rads are hot enough.

 

[Agile]

Virtually all the copntrol is in the first turn of the lockshield valve.

So changes should only be made as a very small angle like 15 ° at a time and the wait 15 min for it to stabilise.

You need a contact thermometer and to aim for a flow/return difference of 15-20°.

Tony

 

[meispete]

Thanks for the replies,

The problem I have is none can really be turned down, as if I turn them down at all the radiator simply doesn't heat up.

If I open any of them any further, then there isnt enough heat to go around to the radiators at the end of the loop, and they remain cold even if opened further.

Also, on a Biasi when the thermostat reaches its desired temp and stops the boiler from firing up, should the pump just stop dead at the same time as the gas supply, or should it pump for a few minutes afterwards?

 

[RichieHoneybucket]

I'd say there's a little more wrong than needing balanced, sounds more like a blockage in your system. Is it a microbore system by any chance??

The circulation pump should run on after the boiler shuts down, it's called pump overrun.

 

[cashjob]

I'm at my whits end with my heating system, as soon as I fix one problem another appears!

I have a Biasi condensing boiler,

The problem is in the first sentence. The answer is in the second!

 

[Servotech]

Also, on a Biasi when the thermostat reaches its desired temp and stops the boiler from firing up, should the pump just stop dead at the same time as the gas supply, or should it pump for a few minutes afterwards?[/quote]





After the boiler switches off on the boiler themostat the pump should carry on circulating I would have thought.
Could be a wiring fault?

Give this a try first if the boiler thermostat is not set to the max, then make it so (Set it to max temp').

 

[SimonH2]

The pump should run whenever the controls (room stat, timer, etc) demand heating - that's ALL the time the controls demand heating. The boiler should then turn the burner on/off (and probably modulate in between) in order to control the water temperature to the setpoint.

If there isn't enough flow to heat some rads with other only that much open on the lockshield then that suggests a pump problem (or a pipe blockage). What speed setting is it on ? Is there a bypass loop, and is it manual or automatic ?

 

[ianniann]

9 radiators, not a lot. Sounds like the pump is not doing its job, or something else is reducing the flow.

 

[meispete]

Thanks,

Think I'm gonna remove the pump and have a look at it and see if its clogged up or dirty inside and take it from there.

If its not, I'll try a DIY power flush.

Been reading up on it and can hire a machine for £65 plus chemicals. Doesn't seem like its too hard?

Also, looks like the Biasi Garda 96.24sm/b which I have doesnt have an overrun?

 

[bengasman]

...Been reading up on it and can hire a machine for £65 plus chemicals. Doesn't seem like its too hard?

I had two jobs in a row that were "powerflushed" by a so called professional but still didn't work. There is a bit more to it than sticking a machine on.

Oh, and just ignore the comments form richie, he is not a pro but a notorious troll who has been barred many times under other aliases.

 

[RichieHoneybucket]

...Been reading up on it and can hire a machine for £65 plus chemicals. Doesn't seem like its too hard?

I had two jobs in a row that were "powerflushed" by a so called professional but still didn't work. There is a bit more to it than sticking a machine on.

Oh, and just ignore the comments form richie, he is not a pro but a notorious troll who has been barred many times under other aliases.

35 years in the trade man & boy. Forgotten more about Plumbing & Heating than any CPS/CCC like you knows son. You & your bum boy mates are all up each others a.ses in the combustion chamber pot!!!....

 

[SimonH2]

35 years in the trade man & boy. Forgotten more about Plumbing & Heating than any CPS/CCC like you knows son.

In other words, you are suggesting that experience with old cast iron boilers of yesteryear somehow qualifies you to speak about modern electronic controls and stuff. You may have kept up to date, you may still be stuck in the 1970s. One thing is for sure, when I hear/read someone bringing up the "I've been doing this for ..." line then more often that not they are stuck in the past.

You & your bum boy mates are all up each others a.ses in the combustion chamber pot!!!....

And personal abuse/insults are supposed to make you look clever ?

 

[RichieHoneybucket]

Simon, I wrongly thought you were quite bright. Nothing in Central Heating has ever changed. Boilers, pipes & emmiters. You can add all the knobs, bells & whistles, but it's not changed in 100+ years.

 

[bengasman]

Don't waste your breath Simon, rh has been caught out many a time despite his latest troll alias being only a few months old.
He may be stuck in the past, but it is not a past as RGI. Look at his posts, and you will see what I mean.