Advice: Power Flushing Failed, What Next?

meep

Looking for some advice on what my next steps should be;

As part of a heating controls + solar upgrade, the company doing the work did a powerflush of our heating system (rads). They also added a magnetic filter to the system.

Our heating had never really worked well in the 10 years since we installed it as part of a major refurbish. Rads never really reached significant heat and many were tepid at best.

During the sales / planning process, the company used a thermal imager to assess the rads and all showed a small amount red at the top, a band of yellow across the middle and a big stack of blue at they bottom. They advised that a power-flush would help shift what looked like sludge build up and the magnetic filter would help things run smoothly in future.

Having had the flush completed, there's really no difference. Even to the touch, most rads are warm (at best) at the top and only slightly above cold at the bottom. (in fairness, some have improved). The system still needs to be balanced but I don't think that's going to address the problem.

So, given the above, what should my next steps be? Is it worth taking the rads off and having them cleaned (a messy job as I understand it) or should we be looking at replacing the rads altogether?

I'm meeting the company later in the week and want to be sure I have an idea of what my options might be beforehand.

Thanks in advance

shane0007

That colour range on the camera is nothing to do with sludge but heat difference. You need to see it under grey scale to have a better image of sludge.
It really does not sound like a sludge issue you have. It is either a circulation issue, kinked primary pipe or weak pump.
Turn off every rad except the farthest rad from the boiler. Turn on the boiler & it should heat red hot from top to bottom.
Let us know how happens when you do that.

meep

Thanks for that. I'll do that this evening and report back.

meep

So, switching off all rads apart from the one furthest from the boiler, that one became red hot (untouchable) from top to about 1/4 from the bottom and was very hot (but touchable) for the bottom 1/4.

What does that tell me?

(guy doing the heating control install said the nozzle in boiler may be too small and he'd recommend replacing it with a larger one)

JohnnieK

meep wrote: »

So, switching off all rads apart from the one furthest from the boiler, that one became red hot (untouchable) from top to about 1/4 from the bottom and was very hot (but touchable) for the bottom 1/4.

What does that tell me?

(guy doing the heating control install said the nozzle in boiler may be too small and he'd recommend replacing it with a larger one)

Do you know the size of the boiler?
It could be the pump!

shane0007

meep wrote: »

So, switching off all rads apart from the one furthest from the boiler, that one became red hot (untouchable) from top to about 1/4 from the bottom and was very hot (but touchable) for the bottom 1/4.

What does that tell me?

(guy doing the heating control install said the nozzle in boiler may be too small and he'd recommend replacing it with a larger one)

Nothing to do with your boiler nozzle.
There could well be a bit of sludge in the bottom of the rad combined with a weak circulating pump. It's most definitely a circulation issue rather than a power issue.
It would be a good system to stick my thermal image camera on as that would determine if sludge was the issue.

oikster

If your system has never been working up to scratch over the last 10 years since you had it installed I would be inclined to suggest an undersized or underpowered boiler or undersized pipework.

shane0007

oikster wrote: »

If your system has never been working up to scratch over the last 10 years since you had it installed I would be inclined to suggest an undersized or underpowered boiler or undersized pipework.

I would have thought any undersized boiler would have enough output to heat one rad all the way to the bottom.

esox28

Op, you say the system never worked upto a comfortable level of heat output from rads from day one of your new system!

How are the rads piped? I mean does the feed to the rads come from the floor up to the rad or was all the pipework installed on the attic and droped down to the rad from the piework above?

Do you have solid fuel boiler attached to your rad system?

Can you isolate the hot water cylinder from being heated by the oil boiler?

How many rads in your system?

Make and output of your oil boiler if you can, you will usually find the boiler data plate on left hand side of the boiler depending on modle.

Billy Bunting

I would have imagined in 10yrs you would have had at least one decent engineer service the boiler and identify that it had the incorrect nozzle fitted.

Sounds like a circulation or balancing issue to me.

Do you have plenty of hot water ??

PS, NOT slating anyone.

meep

Thanks all for the input. I'll try to answer all questions in one post;

I don't know the boiler size but I'll gather what info I have this evening and post back.

Rads are piped from floor up.

No solid fuel heating system attached to rad system, oil boiler only

As I understand it, our new heating controls allow us isolate the hot water cylinder (there's a 'water' zone and water is not heated if wither of the other two zones are on)

There are 21 rads in the system

Previously (before new heating controls) we would have plenty of hot water whenever the heating system was running.


I think that's what everyone was looking for. Diagnosis seems to be coming down to a weak circulation pump or underpowered boiler (we're planning on upgrading to a condensing boiler in a few years) but maybe I'll have someone look into a replacement pump in the meantime.

shane0007

An under-sized pump & an under-sized boiler would heat one radiator all the way to the bottom of the radiator, so me thinks there is also another issue or a combination of issues. Hence, the thermal image camera would determine what is going on at the bottom of the rad.

jimf

meep

you really need to diagnose the problem 100% first before you can expect a fix there are too many ifs and maybes post what area you live in and im sure 1 of the plumber/heating contractors on here will be able to help or point you in the right direction

believe it or not they know their stuff only joking of course

esox28

imo your next step would be to get your guy who done the powerflush to

1. check the resistance of the circulating pump on setting no.3

2. check the output from boiler, not quoted output on the side of boiler but actual output by reading the jets gph and corroborating this info with the stated mi's kw output.

check before you get the guy to undertake this work that he in compantant with oil burner settings and circulating pump repairs.

your circulating pump is probably under sized as in its a 5meter pump when it would need to be a 6meter for a large bungalow type dewelling with long runs to central heatiing rads

meep

Thanks Everyone.

Will certainly need to get someone competent to look at this.

What's become clear is that the problem is out of the scope of the work in the controls upgrade (power flush) so I'll need to get someone to look at this issue specifically.

For the record, the burner is a Riello 40, Model G3B, Type 437T1 with stated thermal power output of 19-25kW

Thanks again.

jimf

was your boiler part of the original installation were any rads added since then

Papa_Bear

Im upgrading my system to a sealed system and in the process of moving the feed pipe I discovered by chance, and to my amazement that the return pipe about 2m from the boiler was completly blocked with solid magnite (sludge). The 3/4 copper pipe when I removed it looked as if someone had jammed a corke into it. Now I have been having circulating problems for years which is what prompted the upgrade in the ifrst place. The system is on its third circulating pump. Having discovered this blockage only today, everything that has been happening over the last eight years suddenly makes sense, from air intake, to poor output, pump noises, cavitation etc.

I would say it might be an idea to check any pipe runs where there are several elbows close together that can accumulate sludge as this is exactly what seems to have happened in my case. Places to look for maybe where two or more pipe returns combine close to the boiler.

In the past I have cleaned out all 6 of my rads and seen the impeller of my first pump completely caked up. You have 21 rads so theres alot of potential slude buildup.

Hope this helps.

meep

jimf wrote: »

was your boiler part of the original installation were any rads added since then

All rads and boiler are part of the original work. Nothing added since.

Peter

ccsolar

meep wrote: »

All rads and boiler are part of the original work. Nothing added since.

Peter

Hi meep
Take off all the rads off the walls and flush them out separately, check the supply pipe from the header tank as we have seen these get blocked up on several jobs
Cc