Boiler woes

[OldJake]

Evening all

We have a Gloworm Fuel Saver F boiler which has been well looked after and is pretty efficient albeit getting a bit old.

Recently it's started making a weird noise. It sounds like a plane flying over. Not loud, but at the end of its firing, it starts quite high pitched and get lower over about 10 seconds, then you get a few clunks. It's taking ages to heat the radiators and also cuts out from time to time and I have to press the reset button on the underneath.

My gut feeling is that it might be the pump rather than the boiler. So if the pumps not doing its job then would the water hang around the boiler to the extent that it boils and overheats?

I've had a listen to the pump and I can hear it running. I doesn't sound knackered like a noisy motor. In my head, it sounds like the blades are broken or something so there's not much surface area hitting the water - more like one of those hand blenders for food.

There are no markings on the pump. I've attached a pic. So, does my description sound like a pump problem? If so, can anyone help with identifying it or suggesting a direct replacement.

Thanks in advance
Andy

IMG_20200319_211327

• OldJake
• 19 Mar 2020

 

[muggles]

The identification markings are on the other side. It's a Grundfos, but I can't tell you which model without seeing the part that's facing the wall!

 

[OldJake]

The identification markings are on the other side. It's a Grundfos, but I can't tell you which model without seeing the part that's facing the wall!

That was quick! Thank you. The issue there is that the plate with the markings is about an inch from the wall. I've found one which is supposed to be an equivalent to Grundfos pumps. I've ordered it. I'll take the pump out when this one arrives. Either it'll fit and I'm laughing, or it won't but at least I'll be able to see the details. With luck, I'll only have to remove the pump once. Worst ways up I'll have to do it twice.

This is the pump I ordered - looks very similar!

https://www.amazon.co.uk/gp/product/B07F8P9ZQJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Thanks again!

 

[Gasguru]

I'm sure the pump police won't be round in these current times...standard efficiency pumps have been illegal for several years.

 

[oilhead]

I'm sure the pump police won't be round in these current times...standard efficiency pumps have been illegal for several years.

So you buy a variable speed pump and leave it set on fixed speed? What's the difference.

 

[OldJake]

So you buy a variable speed pump and leave it set on fixed speed? What's the difference.

Is that what this means? I did some googling but couldn't find anything about this. I wasn't sure if it was a joke and was afraid to ask!

(The comment about the pump police, I mean, not your reply)

 

[oilhead]

Apparently, all C/H pumps should be variable speed to automatically operate at a lower speed when system requirement is reduced by TRV's closing for example. However, on combis they are always set at a fixed speed so that they perform in the DHW mode, so variable speed pumps can be set to fixed speed. In most instances, pumps tend to be left in the fixed speed mode.
It is another example of building regs being out of touch with reality, as with programmers and thermostats which are unnecessarily complicated and often left to run in manual mode. As the tech generation increases no doubt the Nest / Evohome usage will become morenormal, but to many householders, the constant button and a twirly thermostat will remain the norm.
Fit your new pump, set it at 2, if it does not get your house warm enough, then turn up to 3. If the rest of your system is as old as your boiler, it probably would not like variable speed pump, as the resistance of sludge/scaling would reduce speed and therefore circulation.

 

[OldJake]

Cheers for that, oilhead. My house is highly automated. I don't think there's a single light that isn't controlled by a sensor, smart switch and/or voice. The heating uses a Netatmo thermostat which is linked to the weather station in the garden so it adjusts the schedules and everything depending on what's happening outside as well as inside. The boiler is the weak link at the moment. Once pennies allow, it's one of the priorities to replace. I've thought about TRVs but I think they'd be a waste. We all like our bedrooms cold. Radiators are usually low and windows open. The only room that we like warm is the lounge which is where I've got the thermostat anyway.

 

[Gasguru]

Apparently, all C/H pumps should be variable speed to automatically operate at a lower speed when system requirement is reduced by TRV's closing for example. However, on combis they are always set at a fixed speed so that they perform in the DHW mode, so variable speed pumps can be set to fixed speed. In most instances, pumps tend to be left in the fixed speed mode.
It is another example of building regs being out of touch with reality, as with programmers and thermostats which are unnecessarily complicated and often left to run in manual mode. As the tech generation increases no doubt the Nest / Evohome usage will become morenormal, but to many householders, the constant button and a twirly thermostat will remain the norm.
Fit your new pump, set it at 2, if it does not get your house warm enough, then turn up to 3. If the rest of your system is as old as your boiler, it probably would not like variable speed pump, as the resistance of sludge/scaling would reduce speed and therefore circulation.

It's nothing to do with fixed/variable speeds but Erp (Energy related Products legislation from the EU) that has been around for many years and gradually incorporated into heating systems.

The dates for the introduction of these regs. have been constantly changed and reviewed in order for the pump manufacturers to come up with reliable designs.

Back in Aug 2015 the requirement was for boilers with an integral pump to have a high efficiency designed pump.
AFAIR around Sept 2018 the legislation required replacement pumps external to the boiler to be of high efficiency.
The boiler manufacturers have been fighting the EU to delay the requirement that replacement pumps fitted to pre 2015 boilers must also be ErP rated. Originally the date was Jan this year and due to space constraints etc could mean many boilers being deemed obsolete after just 5 years use and made a mockery of energy saving regulations. AFAIK that date has been pushed forward.

All those ebay/Amazon sellers are happy to sell products that meet no legislation whatsoever. I certainly wouldn't fit electrical products that have dubious markings purely from a safety view.

All high efficiency pumps can be set to a fixed speed to operate as a traditional pump (since many boilers require it) but if the pump has other operating modes (and if the system and boiler are compatible) by all means use them but those other modes are just further increasing the efficiency (in theory).

Most of our traditional systems a high efficiency pump makes little energy difference (say £5 to £10 saving per year offset by the higher cost and shorter life).
The only real benefits are with underfloor heating type systems where pumps are on for extended periods (perhaps 24/7).
In fact the ErP regs were based on 24/7 running which really only applies to the heating systems found in Germany and the like and is largely not applicable to the UK but we are/were at the mercy of misguided beaurocrats with zero technical knowledge.

Setting your pump to a variable speed when a boiler requires a minimum throughput can cause long term damage...and a shorter boiler life is hardly good for energy savings.
The vast majority of tech fans in the plumbing forum haven't the faintest idea about heating systems yet they buy into smart stats and all the other eco nonsense not realising the problems they are causing.
Most of these tech firms are based in Californiana...the USA has the most archaic heating systems on the planet. Condensing boilers and modulation is a rarity there and so is the knowledge.

 

[durhamplumber]

My house is highly automated. I don't think there's a single light that isn't controlled by a sensor, smart switch and/or voice. The heating uses a Netatmo thermostat which is linked to the weather station in the garden so it adjusts the schedules and everything depending on what's happening outside as well as inside.

 

[vulcancontinental]

You may have the dates of legislature changes the wrong way round Gasguru.

The Fuelsaver was an excellent boiler I still had one for a customer running sweet 27 years old but the nit wanted to upgrade to a combi in the loft; his loss. The point I'd make is it's a low water content boiler, don't play around with the speeds, put it on manual maximum.

 

[Gasguru]

Quite possibly