Vaillant boiler not heating radiators. Please help!

[Riley]

Sorry if this has been covered but I assume you've tried disconnecting a radiator and seeing if you get water out when heating is on? Is it warm?

 

[Riley]

Also are all you radiators the same

 

[Scott_D]

This is why noone want to take over from someone elses work

 

[Riley]

Exactly. I still reckon the problem lies with the rads or the TRVs

 

[Scott_D]

Did Vaillant charge for the two visits?
Has the heating zone valve been checked? whats on the pipe next to the zone valve for the heating?

 

[Riley]

Thanks Riley.

Looks like I'm left to consider options 1 and 4 then (as vaillant replaced the controls last week)

Also I thought you said that the valves weren't bi directional

 

[Riley]

Hi guys,

Just thought I'd follow up.

Vaillant came out today and replaced the pump in the boiler. They said it was fine but would do it for free as a precaution. Unfortunately the rads are still not getting hot!

That leaves 2 issues - rads piped wrong or poor circulation. I think it's the latter because some of the rads have been piped correctly and none of them are getting hot (even the ones piped correctly).

Now I'm trying to find out who's fault this is. The first plumber ran the pipe work but the second plumber commissioned the boiler. Is it correct to assume that the person commissioning the boiler should have checked the heating before confirming it was ok to put carpets down?

In terms of my options I really don't want to rip all carpets and floorboards up and digging out the chases. Is it worth doing a power flush first? How effective are they normally? I'm hoping that because the first rad in the circuit is not getting hot that the blockage is early on in the circuit.

What would you guys do in my situation please?

Thanks

If you're looking to blame, we don't know the full circumstance of your renovation.

Why did the first plumber not complete the job was there a falling out?
Yes the second plumber should've checked that the rads were heating up but was he working to your timescales was he under pressure to get done to a timescale?

It's difficult for us to comment

 

[Gasmk1]

the photo of the radiator shows it piped up as normal radiator but instructions say should be top and bottom if all rads are the same this may be your problem

 

[Rystar00]

Sorry for the late reply guys. I will try and answer your questions below!

1. I haven't tried disconnecting a radiator but they are all filled up (I've bled them all)

2. Some radiators are warm, some are stone cold (so not all the same)

3. I've checked the specs of the valves and they ARE bi-directional (sorry I'm a novice when it comes to plumbing)

4. I'm not looking to blame anyone for anything. I'm just trying to understand if it's customary for a plumber to check that the rads were operating properly when commissioning the boiler as we only laid the carpets when he said he'd commissioned it.

5. The first plumber was my child hood friend. Unfortunately we fell out as he prioritised other jobs after I'd paid him in full up front and left me in difficult situations with other trades when he kept failing to show up. I wish we'd never fallen out!

6. Vaillant didn't charge for the first visit as they replaced the controls which were faulty. They did charge for the second visit as they said the boiler is working fine but there is poor circulation in the system.

I'm in a tricky spot as everything has been plastered and flooring laid. I ran out of money (was messed about a few times by various trades) so had to try and finish stuff myself and I can't afford to rip everything up and start again

How effective would a power flush be at removing a blockage? I have uponor pipes everywhere apart from copper coming out of the boiler.

 

[Riley]

It doesn't sound to me like a blockage. I'd say more likely a piping issue

 

[Scott_D]

It sounds like plumber no 2 comissioned the boiler not the heating system

I doubt a power flush will do any good

Why not use some of that money to pay no 2 or someone new to come back and look at the heating system

 

[Rystar00]

Thanks again guys.

I'm out of pocket twice now (paid plumber 1 in full and he walked off before it was complete and plumber 2 obviously needed to make it worth his while). I'm now way over budget without a properly working system!

So would the person commissioning the boiler not check that the radiators pumped out heat please? Plumber 2 fitted the towel rails and they're not getting hot either.

 

[Riley]

It's likely a piping problem. Drain and remove one non working rad turn on heating and open each valve into a bucket is the water hot?

 

[Scott_D]

So would the person commissioning the boiler not check that the radiators pumped out heat please? Plumber 2 fitted the towel rails and they're not getting hot either.

In theory yes, but only you and he know what you agreed/paid for

 

[macackau]

4 storey house and a system boiler? I don't reckon the pump is up to it. Needs a bigger pump

 

[Rystar00]

Unfortunately I know nothing about plumbing so thought commissioning the boiler entailed checking that it actually caused heat to come out of the radiators. There is a danger if you spell things out to the nth degree that the installer thinks you're an idiot whereas I'm quite easy going and try to be nice to people.

I've just turned off all of the rads apart from the stone cold one. It made a big gurgling sound near the boiler and now some heat is slowly going to it.

What is the sound likely to mean please? Should I keep running the heating? I don't want to push the blockage further along out of reach and under the tiles by keeping it running!

I've bled the rad and warm water is coming out but not hot.

 

[Stoney Ground]

Now you've bled it check it stays warm, the gurgling noise will be air.

If it stays warm, then slightly open the next furthest Rad from the boiler and see how that does.

May need balancing to get an even heat distribution.

 

[Riley]

Did we get an answer???

 

[Rystar00]

Hi Riley,

Thanks for following up!

No update as of yet as the plumber hasn't been available. He is coming in to do a power flush on Thursday. I haven't got the skills to do what you suggested but bled the radiators and the water seems to be lukewarm even though the heating was on max for a couple of hours. What do you think that means please?

I obtained manufacturer instructions and some of the radiators (4 out of 12) can be piped either way and those aren't getting properly hot even with the others shut off so I'm not sure what the problem is.

I think it could be the pump not being up to the job (which is strange as the Vaillant engineer said it should be ok) or some sludge in the system.

I'm going to add some Sentinel x300 tonight and see if that improves things before the power flush is done on thursday. if that doesn't clear it up then will ask the plumber to fit a secondary pump.

If that doesn't work then I'm at a bit of a loss!

 

[Riley]

Have we definitely confirmed if valves are bidirectional

 

[Rystar00]

Hi Riley,

I have two types of valves on my system; the first type are bi-directional (these: http://www.NoLinkingToThis/p/white-chrome-angled-trv-15mm/60368)

and the second type are tradiaitonal valves that can be used at either end (these: Traditional Chrome Angled Radiator Valves Pair 15mm)

 

[Riley]

Ok. Worth a try

 

[Rystar00]

Hi guys,

A quick update.

I flushed the rads manually with a hose pipe a couple of weeks ago and when I drained a rad last night to add Sentinel X300 the water was clear.

However when I removed the bleed valve to dose the chemical loads of carp started coming out of the rad. This is a tiny rad! Now the pump in the boiler only seems to work on 'max' when there is a demand for hot water and doesn't seem to work as hard as when there is a demand for heating.

Is this normal in a system that is only a couple of months old? The original plumber did say that there was an unusually large amount of debris in the radiators given they were brand new.

 

[ShaunCorbs]

No that's not normal but can happen needs to be flushed, chemicals in leave it as long as possible read the instructions and if you can take each rad off and flush with hose while beating gentle with a rubber mallet

aldo do you have a mag filter by the boiler ??

 

[Riley]

I would be getting onto the radiator company as well as I bet they weren't cheap Y

 

[Rystar00]

Thanks guys. I really appreciate your help as the house renovation has been so stressful and this is topping it off! Especially considering

Yes I have a magna clean but none of these particles are being trapped. The water samples are all clear - it's just when I took the bleed valve off that I noticed all of these debris particles coming out!

Do you think it's worth asking the radiator company to pay for the power flush?

 

[ShaunCorbs]

Thanks guys. I really appreciate your help as the house renovation has been so stressful and this is topping it off! Especially considering

Yes I have a magna clean but none of these particles are being trapped. The water samples are all clear - it's just when I took the bleed valve off that I noticed all of these debris particles coming out!

Do you think it's worth asking the radiator company to pay for the power flush?

You could ask but bet you there's something in the small print saying must flush the rads out first

 

[Rystar00]

Just checked the instructions and it says I must flush the heating system out first not the radiators (the plumber did this when commissioning the boiler). I will write to them and see what they say.

What I'm concerned about is each of these radiators having some debris in them and when the boiler was fired up it circulated the debris and it's all collected somewhere which is causing the poor circulation. Don't know what il do if I have to rip floors and carpets up!

So weird that the water is clear when draining and in the magna clean but there is a load of carp near the bleed valve that seeped out when I added the chemicals!

 

[Riley]

Sometimes carp does collect at the threads. I think there's more to th than meets the eye. Do any of the radiators warm up properly

 

[Rystar00]

Yes some of them warm up more than others. If I turn off all valves apart from one rad then that one gets roasting.

Just read up on 'sludge Flakes' and I'm worried that my picture shows them. Apparently they're difficult to remove with a power flush. Getting really worries now as the system was piped in uponor so unlikely that there was any flux etc left in there and that all these flakes have come from the radiators and have collected somewhere and we won't be able to remove them.

 

[Riley]

The positive being that if each rad will get hot when it's on on its own then you have circulation.

 

[Rystar00]

Thanks Riley.

One radiator in particular only gets lukewarm when I isolate it. 90% of the others get hot. Is that a bad sign?

Unfortunately that's the one with pipes under our tiled floor!

 

[Riley]

There's nothing to say that the pipes for that rad can't be isolated at either end

 

[Rystar00]

Hi guys,

Me again!

Just thought I'd keep this post updated in case anyone reads this thread and has similar problems.

Had the installer in today and we've ruled out blockages in the pipe work and the radiators being piped wrongly.

If you remember - the boiler heats the hot water really well (burner on max and flow temp at 70 degrees) but when the demand for hot water was satisfied it started hearing the rads but flow temperature would start at 70 degrees and then lower until it hovered around 45 degrees. This happened even though we disconnected the Internet (so no weather compensator data used), the room stat in the fridge (3 degrees) and 'comfort override' mode on.

We then tricked the boiler when it was heating hot water to heat the rads instead (at 70 degrees with burner on max) by manually opening the motorised zone valve. All of the radiators (bar a couple that had dodgy valves which we've now fixed) and all the rads were roasting. So the pipe work and rads are fine.

So the installer thinks it might be the controls. However Vaillant have come out twice and not identified the problem. I think it might be the fact that the boiler is oversized (30kw but have 14 rads over 4 floors plus unvented cylinder) so it might be in anti-cycling mode? What do you think?

 

[ShaunCorbs]

I still think it's something to do with weather comp it's the only thing other than somthing drastic as its prity much all standard kit wired to s plan

 

[Rystar00]

Thanks Shaun.

Why do you think that is please?

As far as I'm aware the weather comp data is collected from the Internet so with that switched off it has to rely on the room stat which was sat in the fridge?

Tempted to get a bloody basic on / off switch instead!!

 

[Riley]

I do agree with Shaun re the symptoms. I just can't see how with a v smart as there's no external sensors

 

[Riley]

Switch might be a good place to start

 

[ShaunCorbs]

The reason I say is if it was one of the controls not much on the heating side port valve and room stat it would be doing it for both heating and hot water

The only way other than to remove anything regarding weather comp is wait for the cold weather and see if it heats up then

Unless you could trick the weather comp to think you living in the North Pole if you have to set it manually where you live ??

 

[Riley]

Hang on hang on hang on just re-read your first post do you have a room thermostat in addition to the one that comes with the V-smart

 

[Rystar00]

Sorry Riley!

I have the vsmart which comprises of a VR65 wiring centre and a separate room stat (comes in the same box)

 

[Riley]

I'm reckoning wiring fault did Vaillant guy check wiring

 

[Stoney Ground]

We then tricked the boiler when it was heating hot water to heat the rads instead (at 70 degrees with burner on max) by manually opening the motorised zone valve. All of the radiators (bar a couple that had dodgy valves which we've now fixed) and all the rads were roasting. So the pipe work and rads are fine.

By doing what I said in post 45, 3 weeks ago you would have proved this.

 

[Riley]

I'd get Vaillant back mate you've proven the system works

 

[Rystar00]

Thanks Riley - I will get them back. They said to change the range rating on the boiler downwards but that's had no effect. I understand from searching other forums that I'm not the first to have had this problem.

Stoned Ground - fantastic advice thank you. I showed your post to my installer (he probably hates me now!) and he followed those instructions to identify the issue.

I will keep you posted on what happens next.

 

[Stoney Ground]

Sometimes it's easier to take away external controls to prove they are or aren't the problem. Maybe ask Vaillant to send a senior technician they need to prove to you there is not a fault with their system.

Have they tried a full factory reset of boiler and controls?

 

[Rystar00]

I thought it might help if I took the boiler from 'auto' under the heating load to the actual load.

I have calculated my rad heat output as 18,137kw so how much should I allow for my unvented cylinder please? 2kw? Would it then be a good idea to set the heating load at 22kw?

Thanks again guys!

 

[Riley]

Right you've proven that your radiators get hot yes ?
You did this by essentially taking the zone valve out of the equation?
I think you are looking at a control or a wiring issue
I'm not sure that there is a kilowatt loadage issue

 

[Rystar00]

Hi Riley,

Thanks again for your support. Your advice has been incredibly helpful and generous.

Yes we have established that the rads get hot (by manually opening the zone valve when the boiler 'thought' it was heating hot water) so the installer agrees and thinks it's a wiring/control issue.

I thought adjusting the load might help as I wonder if the boiler is going into anti-cycling mode too quickly if its oversized? It's probably something as simple as the wiring or controls but I've read other forums that have posts with similar problems to mine and that's what they suggested.

 

[Riley]

Have you got Vaillant coming back I think you are just clutching at straws a bit at the moment mate you need to go at this with a plan rather than just randomly changing stuff in the hope that it will fix it. My suspicion would be that there is an issue with the wiring centre