4 rads not heating, Pump issue?

NobodyImportant

Hi all,

Moved into an old, cold house in January. The radiators were all clogged up to bits with 20 years of crud.

I had it powerflushed in February and it was night and day. The house heated up in an hour instead of 3 hours.

After this, 4 radiators (on a 12 radiator system) werent heating properly at all. The inlet was warm, the top of the rad was warm, but the outlet pipe was cold. The radiators are a bit random, one downstairs, 3 upstairs.

So i figured clogged up valves.

I shut all the radiators, changed the 4 outlet valves, checked the pipe and rad for blockages. Turned on just those 4 rads and hit the heat on again.

Perfect. All toasty hot. Turned back on all the other rads, those 4 went cool again.

So when just those 4 are on, its piping hot, but when the whole system is on, they go luke warm at best.

Is it a case of the pump isnt powerful enough?

Thanks,

demanufactured

The rads need balancing I'd say.

NobodyImportant

Do you think? I'm not entirely convinced.

Reasons why are that on one wall downstairs, you have a radiator each side of the wall. One is barely warm, the other is roasting. Changing the inlet/outlet on the luke warm radiator doesnt do anything. On a rad just 4 from the boiler, i would have thought it shouldnt have a balancing issue. Same upstairs, it doesnt seem to matter about the location of the rad on the system.

I do need to get rad thermometres and balance them properly, but it just seems odd that it would be a balancing issue.

Any tips for balancing on a non TRV systems? Leave all lockshields fully open? Start from the boiler or work backwards?

Thanks.

demanufactured

NobodyImportant wrote: »

Do you think? I'm not entirely convinced.

Reasons why are that on one wall downstairs, you have a radiator each side of the wall. One is barely warm, the other is roasting. Changing the inlet/outlet on the luke warm radiator doesnt do anything. On a rad just 4 from the boiler, i would have thought it shouldnt have a balancing issue. Same upstairs, it doesnt seem to matter about the location of the rad on the system.

I do need to get rad thermometres and balance them properly, but it just seems odd that it would be a balancing issue.

Any tips for balancing on a non TRV systems? Leave all lockshields fully open? Start from the boiler or work backwards?

Thanks.

Do you know where all the pipe runs are??
A rad close to the boiler might not necessarily be close to it in terms of pipework if ya get me.


In my house (solid fuel stove only), the pipework runs up to the hot press and then a secondary flow and return is run for the upstairs rads.
There is a drop halfway along this run for the downstairs rads...one of which is in the same room as the stove.

NobodyImportant

I dont know exactly the route, but i have a rough idea. When one rad downstairs is cold and the others warm, then the 3 upstairs are nearly split in opposite ends again, it just doesnt make huge sense. But i could be wrong.

There are two places where rads almost next to each other are opposites in terms of temps.

jimjimt

Might need another clean. 20 years of crud may take more than one flush.

wandatowell

A side issue,

How often should you flush the system?

jimjimt

Every five years would be good from new. More so because all modern radiators have thin channels and all modern boilers have heat exchangers.
Another option is to flush and then fit a Magna Clean. They are mighty for keeping a heating system clean.

NobodyImportant

So I balanced the system last night.

I opened all the flow valves and only opened the return valved by 180 degrees. I opened the bad rads fully. Small improvement, but not much.

Checked the pump, it was warm to the touch, but not hot and its on its highest setting.

NobodyImportant

This is the pump. Its a surepump SP 55/130.

2330 rpm on its max setting. Having more pressure to those rads (closing the others) allows flow through them.

Do you think i need to upgrade the pump? Can you flow more? If the 4 rads are blocked, is it worth another powerflush (€250?) or should i just replace the rads?

The system currently has 12 radiators, the second floor is higher than a normal house as the ceilings are higher and its a fairly long run from the pump to say the last rads upstairs (house is very long and narrow).

jimjimt

The sure pump is not a bad pump. It comes from Dab which is owned by Grundfos. But it would not be as good as an original Grundfos pump. If it is a really long run upgrading to 6m Grundfos pump will improve the heating system.

Perhaps change the smallest of the rads not heating, just to see what happens.
Power flush v changing rads depends on the size of the rads and costs?
If the rads are twenty years old new rads are going to perform better.
Regardless if you were going to put in all new rads you would have still needed to clean your heating system.

No harm to put in more cleaner for a couple of weeks at the end of the heating season and give it a secondary flush. 250 was a good price for it.
Then change the pump and rads if required.

Form looking at the photos you have a lot of damp around the boiler ?
Any concerns from all the damp ?

You have a old Ferrolli Oil Boiler ? About 75% efficient.

NobodyImportant

No, no major concerns about damp in the boilerhouse. It is a bit damp, but I'm doing damp works outside of the boilerhouse to relieve any issues, digging trenches, airing soil under the deck better etc.

Yes its a Ferrolli. I think I'm just going to hang onto it until it blows up. It might be one of those old but unbreakable types and thats fine for me rather than trying to get an extra 10-15% efficiency and spending a huge wad of money.

I might take up your suggestion and just swap out one the the underperforming radiators and see if it suddenly warms up. If not, i will then head for an upgraded pump.

The whole system is pretty old at this stage.

Thanks for the advise.

Dtp79

NobodyImportant wrote: »

No, no major concerns about damp in the boilerhouse. It is a bit damp, but I'm doing damp works outside of the boilerhouse to relieve any issues, digging trenches, airing soil under the deck better etc.

Yes its a Ferrolli. I think I'm just going to hang onto it until it blows up. It might be one of those old but unbreakable types and thats fine for me rather than trying to get an extra 10-15% efficiency and spending a huge wad of money.

I might take up your suggestion and just swap out one the the underperforming radiators and see if it suddenly warms up. If not, i will then head for an upgraded pump.

The whole system is pretty old at this stage.

Thanks for the advise.

Is the balance valve on your cyclinder fully open? Also 250 was quite cheap for a flush. Are you sure it was flushed properly? How long did the plumber spend flushing the system?

DGOBS

I would agree €250 seems too cheap, a proper flush may cost in excess of €100 just for chemicals and require at least 2 site visits, the second visit may take up to a day.

gdavis

I would also make sure gate valve on cylinder return is not fully opened,and from cold system turn on boiler and note which rads heat first second etc. and which rad valve on each rad gets hot first too to make sure u kn ow which are the flows to rads as lockshield could easily have been put on flow,then open fully all flows and close all returns,then first rad on circuit open return half a rotation and second rad,a bit more etc. see how u get on with that

NobodyImportant

Yes I was happy with the flush. I put the chemicals in myself a week previously and let the it run around the system. Then each rad was flushed one by one using the proper machine. Amazing amount of crap came out. MASSIVE improvement, i couldnt get over it.

Thanks GDavis, i closed the gate valve about halfway, didnt seem to make a huge difference.

I think its nearly certain i need to upgrade the pump. Its a very long run just to get from the boiler house to the front of the actual house and then its at least 5 metres from the pump to the second floor rads vertical, let alone the 3rd floor radiator (and its an old pump), so i would say the 6m head should help boost the system.

Those rads that are underperforming perhaps need another flush.