Vaillant boiler not heating radiators. Please help!

[Rystar00]

Hi guys,

I would really appreciate your expert advice.

To cut a long story short I have recently renovated my house from top to bottom and had a new CH system installed. Key points below:

1. Vaillant Ecotec Plus 630 boiler
2. Vaillant vSMART System Controller (with a room thermostat)
3. Unvented HW cylinder
4. 13 radiators
5. 3 x towel heaters
6. 4 floors (my house is an old victorian terrace that’s narrow and short but tall!)

We had a plumber do the first fix but he badly let us down and disappeared so we asked another installer to finish the job. The second installer has commissioned the boiler.

The hot water is working absolutely fine. However the radiators are not getting hot. Some are completely cold. The system was flushed and all of the TRVs are set to fully open. Turning some of the TRVs off only has a marginal improvement on the heat output of the ones that remain on.

The installer came in to have a look and noticed the following:

1. HW demand caused the boiler to work at max output (the burner modulation graph was working maxed out and the flow temp was at 75 degrees)
2. As soon as as the demand for HW is satisfied and it turns to the CH the flow temp reduces to about 35 degrees
3. There is not much difference between the flow/return temperatures
4. Putting the room stat in the fridge didn’t cause the boiler to work harder
5. Turning off the weather compensator and running comfort mode didn’t cause the boiler to work harder

Vaillant sent an engineer out and he replaced the vSMART because of some dodgy wiring but running the same tests haven’t improved anything. He didn't stay around long enough to diagnose whether there was another problem.

I’m now absolutely desperate to get the heating working properly before it starts getting colder. Would you mind giving me a list of anything that could cause this problem (faulty boiler, faulty rads, needing a secondary pump etc) or things for the installer to try to get this fixed please?

 

[Riley]

Was it all new pipes

 

[Rystar00]

Hi Riley,

Thanks very much for helping!

Yes all new pipes - 22/15mm uponor to the rads - copper coming out of the boiler.

 

[Riley]

Is the property zoned sounds large enough to be

 

[Rystar00]

No it's only on one zone

 

[ShaunCorbs]

Sounds like weather comp is holding the boiler off

 

[Rystar00]

Thanks Shaun.

I switched off the internet so WC wasn't available, put the room stat in the fridge and put comfort override mode on and the flow temp still wasn't staying on for that long (1 minute or so at the most) - certainly not long enough for the rads to get up to temp.

I'm worried that the rads are faulty - or I need a secondary pump to circulate the hot water?

Would changing the kw settings of the boiler help?

 

[Riley]

Rads will not be faulty. Are the TRVs bi directional?
Secondary pump sounds excessive for house size
What KW is it on

 

[Rystar00]

Thanks again Riley. The TRVs are not bi-directional and all are set to max.

The KW setting is on factory auto I believe - do you think it's worth changing this (I've seen other posts where it said to do this) but I don't know enough about heating to decide what to change it to!

On a separate note the original installer hung some of the rads (column rads) on the wrong way around which meant that some of the rads weren't getting hot (as the flow pipe needs to go to the correct inlet) but the installer guessed which ones weren't on the right way and swapped these around (but we can't be sure they're now correct!). Even so some of them should still be getting hot!

 

[Riley]

That could be your answer if TRVs are on return

 

[Rystar00]

Thanks Riley.

Forgive me for being stpid but would that make a difference if the TRVs and lockshields are all fully open?

 

[Riley]

Means that the water will only flow one way even when open

 

[Riley]

And you're right column rads can be very specific in terms of piping

 

[ShaunCorbs]

Thanks Shaun.

I switched off the internet so WC wasn't available, put the room stat in the fridge and put comfort override mode on and the flow temp still wasn't staying on for that long (1 minute or so at the most) - certainly not long enough for the rads to get up to temp.

I'm worried that the rads are faulty - or I need a secondary pump to circulate the hot water?

Would changing the kw settings of the boiler help?

Is there an outdoor sensor ??

 

[Rystar00]

No there is no outdoor sensor apparently.

Just spoken to the installer and he said he turned up the kw output to max (rather than auto) so I'm literally at a loss what to do now!

 

[Riley]

Vsmart is all based on internet

 

[Riley]

If your TRVs arent bidirectional then I bet they're just piped wrong

 

[ShaunCorbs]

Turn all but one rad on and do this for each Feel the pipes hottest first should be with the trv

 

[Riley]

I can't understand somebody not using bidirectionals these days

 

[ShaunCorbs]

I can't understand somebody not using bidirectionals these days

Extra cost is the only reason but not by much think it's down to under £2 per valve these days

 

[Riley]

I reckon that's the problem though don't you Shaun

 

[ShaunCorbs]

I reckon that's the problem though don't you Shaun

Either that or Pipework fault or rads piped up wrong eg top bottom etc

Op can you put some pics up of the install ?

 

[jonnyswamp]

All good advice above, did the original installer fit an auto bypass valve anywhere, usually just under the boiler
Or he may have even fitted the pipe work between the flow and return and planned on fitting valve at a later date before filling/commissioning
This could cause a short circuit and the symptoms you describe

 

[ShaunCorbs]

But I still think weather comp is holding it back get your gas safe Eng to disconnect it and see if it works

 

[ShaunCorbs]

All good advice above, did the original installer fit an auto bypass valve anywhere, usually just under the boiler
Or he may have even fitted the pipe work between the flow and return and planned on fitting valve at a later date before filling/commissioning
This could cause a short circuit and the symptoms you describe

But the boiler temp wouldn't stick at 35 dc

 

[Riley]

The weather compensation is built into the V smart controller mate you connect it to the Internet add your postcode and it takes weather updates from the Internet

 

[Riley]

Internal bypass isn't it

 

[ShaunCorbs]

The weather compensation is built into the V smart controller mate you connect it to the Internet add your postcode and it takes weather updates from the Internet

Will the boiler work without it for a test ?? Not good with vailliants

 

[ShaunCorbs]

Internal bypass isn't it

Unless it's a system boiler always stick one in

 

[Riley]

I would've said just disconnecting from the Internet will do it as you have a separate wireless thermostat as well

 

[Riley]

I'm leaning more and more to the radiators been piped wrong

 

[ShaunCorbs]

I'm leaning more and more to the radiators been piped wrong

What's getting me is the flow temp sticking at 35 if rads / Pipework were wrong would just short and over temp would think ??

 

[Riley]

I think the OP Did say that some of the radiators get Warmish???

 

[jonnyswamp]

Ah give me a slap, I didn't read the 35 degree bit

 

[ShaunCorbs]

Ah give me a slap, I didn't read the 35 degree bit

It's a Friday

 

[Gasmk1]

sounds like the weather comp also its summer so it would run very low temp the only way to be sure is to remove the weather comp and run as normal boiler. as for rads fitted wrong some manufacturers put a small dimple in the header to let you know thats the bottom/top.

 

[Rystar00]

Thanks very much again guys. Will upload a pic of the install when I get home in half an hour.

To answer some of the questions:

1. I'm not sure if a bypass valve was fitted. It's an invented cylinder system. Will you be able to tell by the picture I will upload?

2. I turned the Internet off so it couldn't take data from the weather (put comfort override on which makes it operate according to the room stat). I put the room stat in the fridge to trick it into thinking it was cold. The flow temp reaches 75 degrees very briefly (less than 1 minute) and goes back down to 35 even though I'm asking for 30 degrees from the rads.

3. I have got the instructions for the radiators here. Will upload them and a pic of the rads. Silly question but is it possible to hang rads upside down (ie the flow and returns go where the air vent and blanking plug should be) as well as the flow and returns being in the wrong hole?

 

[ShaunCorbs]

Your rad instructions should tell you which way is best / any no nos

 

[Riley]

Thanks very much again guys. Will upload a pic of the install when I get home in half an hour.

To answer some of the questions:

1. I'm not sure if a bypass valve was fitted. It's an invented cylinder system. Will you be able to tell by the picture I will upload?

2. I turned the Internet off so it couldn't take data from the weather (put comfort override on which makes it operate according to the room stat). I put the room stat in the fridge to trick it into thinking it was cold. The flow temp reaches 75 degrees very briefly (less than 1 minute) and goes back down to 35 even though I'm asking for 30 degrees from the rads.

3. I have got the instructions for the radiators here. Will upload them and a pic of the rads. Silly question but is it possible to hang rads upside down (ie the flow and returns go where the air vent and blanking plug should be) as well as the flow and returns being in the wrong hole?

As far as I'm aware this boiler has an internal bypass

Has the heating ever worked? Do you get any errors at the boiler?

Yes it's possible but unlikely. Usually if manufacturers specify a way to pipe the rad they will add stickers or some sort of indicator

 

[quality]

does the vailliant system have a base setting for heat demand ?

 

[Rystar00]

Hi guys. Looks like the boiler is now firing up to full temp.

Have attached some pics to this post.

Some of the radiators (not all) are warming up but the heating has been running for 2 hours and I would expect them to be almost too hot to touch. Some are still stone cold (valves are open) and some which were previously hot are now cold! I'm so confused!

 

[Riley]

When was it installed???

 

[Rystar00]

Double post

It was fitted by the first plumber in September 2015 but not commissioned until 2 months ago. It was a long renovation,

Hot water been fine but heating always lukewarm

 

[ShaunCorbs]

by the looks of it rads installed wrong well going off instructions thats is

do a test

get the installer to turn hot water on (heat the cylinder) and manually open the two port to the rads (heating circuit) not via the head

does the heating work then?

 

[Stoney Ground]

First thing I would do would disconnect all controls and link out boiler to run totally independent, manually open heating zone valve.

Close all lock shield valves except furthest rad, check it heats up and identify F&R and if rad is piped as per instructions.

You could have 4 problems causing same effect
1. Rads piped wrong (shows top/bottom same end)
2. TRVs on return
3. Controls
4. Pump not man enough.

Solve each one in order, don't try to solve all at once.

Then repeat for next nearest rad, closing previous ones

 

[Rystar00]

Thanks very much guys. It's very kind of you to help

I have a vaillant engineer coming out on Saturday to rule out anything with the boiler. If it isn't the boiler I will show this thread to my installer.

Out of interest would it matter if the TRVs were on the returns if they're bi-directional please?

 

[Riley]

No if they are bidirectional that's what they're designed to do so it doesn't matter which pipe they are on

 

[Rystar00]

Thanks Riley.

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

 

[Riley]

Thank you for coming back please keep us posted

 

[Rystar00]

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