Central Heating Failed

[MTK]

Well I'm not too cold yet but the house is defiant cooling down!!!

I have a fairly conventional gas fired boiler (1989) pumped from upstairs with a diverter valve for central heating / hot water, and a mains-pressure sealed hot water tank.

The heating was working fine until this afternoon. This failure was quite sudden. The switching system (timer plus thermostat all seem to be working fine). The boiler still fires up (until it gets too hot) but the water doesn't seem to be getting to the radiators or the hot water tank. The heating cistern (in the attic) has water in it. When I bleed the upstairs radiators, they bleed water immediately. The pump (Grundfos Type UPS15-50x18) seemed to be making an odd ticking type noise.

It was just after 4pm so I figured a plumber / heating technician wouldn't get to me today and decided to have a closer look at things myself.

I removed the pump seep cover and some water dripped out (good). The pump spindle spun (manually) quite freely. I removed the pump to have a gander myself. The inlet and outlet looked pretty clogged-up with glogging-up material (the inlet unsurprisingly, more so) but I didn't expect them to be spotless. The outlet piping before the shut-off valve had some significant-sized pieces of glogging material with the look and consistency of a crumbly brick. The water I collected from all the leaking when removing the pump (plus, on an ongoing basis, seepage from the outlet plumbing where the shut-off valve wasn't doing a perfect job) seems relatively clear with no huge amount of sediment.

When I refitted the pump and put a stethoscope to it is sounds as if it is spinning smoothly when the heating system is on (and in each of its three selectable speeds) - but for all I know it may not actually be spinning at all!?

I'm guessing, pump, diverter valve or blocked pipe.

inlet:

outlet:

Does anyone have any ideas / prognosis /questions please?

 

[ianmcd]

your system is seriously contaminated and needs cleaning, you will get different quotes for chemical flushing and power flushing but there is no getting away from it your system need clensed

 

[45yearsagasman]

Take a look at your expansion tank and check the water colour.
Your system needs cleaning, but the cause of that bright orange deposit needs investigation. It indicates highly oxygenated water. You may have a blocked cold feed.

 

[MTK]

Thanks for your replies.

In the scheme of things, i.e. it is winter and I have no heating, can I just replace the pump first?

In addition to the corrosion, what would seem to be the likely cause of sudden heating failure please?

 

[Agile]

That colour indicates recently oxidised steel!

Possibly formed by pumping over.

The FAQ on this site has lots of useful info.

Tony

 

[MTK]

Tony, thanks for your reply.

Please excuse my ignorance, but what is 'pumping over'?

Also where can I access the FAQs - and what should I look for please?

Is it likely the pump has failed? Would it make sense to replace the pump tomorrow, get some form of heating back and then plan for a cleanse of some sort in the spring?

 

[ianmcd]

yes changing the pump will be a quick fix and will get things going but you will have to get the system sorted soon

 

[MTK]

Many thanks for all the ongoing help here.

So from the information I have given, and notwithstanding that the system would benefit greatly from a cleanse of some sort, would you say the pump is the mostly likely point of the sudden failure?

 

[onecog]

undo the large silver screw in the centre of the pump and put a screwdriver in to see if it's spinning......you will feel & hear if it's working.

 

[ianmcd]

PUMP is probably the most wrongly used term in a heating circuit it is a circulator not a pump, it can circulate it cant prime or PUMP water and as such being restricted like yours is it cant do its job it circulates water not rusty mud

 

[45yearsagasman]

Boiler is also a misnomer, as the last thing it's expected to do is boil the water.

 

[MTK]

Take a look at your expansion tank and check the water colour.
Your system needs cleaning, but the cause of that bright orange deposit needs investigation. It indicates highly oxygenated water. You may have a blocked cold feed.

Expansion tank water seems quite clear.

 

[MTK]

undo the large silver screw in the centre of the pump and put a screwdriver in to see if it's spinning......you will feel & hear if it's working.

If I do that in a live system;
(a) won't I be at risk of being soaked by scalding water?
(b) even if the spindle is spinning will there still not be a doubt as to whether the impeller is working (maybe the impeller is heavily worn or even disintegrated?

 

[onecog]

You won'y get scalded and if you want to inspect the impeller you can switch everything off, undo the allen keys and pull it apart .

 

[onecog]

before taking the pump apart turn the iso valves off.