KW rating of boiler

[newbuildinstaller]

All I'm trying to get at, is why would I want to offer free specific advice on this matter, on here, on cc or to Joe Bloggs the heating engineer at the suppliers? I don't give free advice when other engineers want to spend a day with me.

erm because you posted on a "DIY advice" site not a "I know but not saying" site.

PS while you lot were out partying I cured cancer last night!! Not going to tell anyone how though. Although for proof I once cured another disease not telling you how I did that either!!!

 

[JBPHS]

PS while you lot were out partying I cured cancer last night!! Not going to tell anyone how though. Although for proof I once cured another disease not telling you how I did that either!!!

Ok smartar5e, if you've cured cancer, I'm sure you can pop round and sort my father, diagnosed with myloma for over 18 months, (who has been told before Xmas that he will receive no more chemotherapy as it's not working) and has been in hospital with pneumonia over the new year, so you can sort him out with your free cure!

I take it that you don't actually work and that when a customer calls you out to remove a radiator that you turn around and say "Yes sir, all you need to do is isolate the system, working safely, drain the system using that drain off there that may be stuck, lift the floorboards, remove the radiator and pipework above the floor, clean the ends of the pipes, cap off the pipe work using those fittings, some flux, solder and heat, refill system, check for leaks, test the system and refit the boards." Whilst you stand and watch FOC drinking numerous cups of tea.

Unlike you all appear to be gentlemen, I am not a millionaire, so I will provide advice on how to sort things properly, as I see on quite a regular basis where installers advise DIY'ers how to carry out work on gas fittings, more commonly, boilers.

Before anyone comes on saying, oh look you touched a nerve, yes newgasinstaller did indeed touch a few sensitive nerves!

It's easy when you don't know someone isn't it newgasinstaller?

James

 

[fezster]

Alright, lets all relax. I thought I was the one supposed to be getting stressed out by my heating system!

Tbf to James, there's been a lot of suggestions, particularly on the other thread, and im sure the correct answer may be in there. If the answer is changing a setting on the boiler or adjusting a valve, im happy to try it. If its changing out a part or adding something, im incapable of doing it. Given ive already wasted money on solutions which haven't worked already, even if im given the right answer, I want to be sure it will work, and ill still need someone to come and do it. From my perspective, if the guy offering the solution is giving me a guarantee it will work or no fee, I dont see that as a problem. As long as the cost is fair for the work to be done (and within my budget!).

Some more info. Boiler was heating downstairs and cylinder from about 12. Hot water was being used to shower the kids at the same time. I turned heating off at 12.30 to see how long the cylinder takes to heat up. Boiler continued to fire for about 20 mins, modulated right down to barely audible. Flow temp 70 degrees, return creeping up past 60. Then boiler shut down. D2 is set to 5, so anti cycle time in d67 is 2 mins. Boiler has now been short cycling for the last 40 mins.

Ive increased d2 back to 20, but as suggested previously, maybe I need to increase to 60. Once the boiler gets in this state, it doesnt seem to recover. Im guessing I need to allow the return temp to drop sufficiently to allow it to fire up and modulate down past the 50 seconds. Tbh, im disappointed it turned off when it had modulated down.another 10 mins at 70 degrees, I believe cylinder stat would have been satisfied. HW target temp is 60 degrees, roughly 7pm on the megaflow stat.

 

[Norcon]

Well why dont you join the CC then show off you work in there then

Typical response from someone in Lancashire and yes you did win the war of the roses lol.

I take it you know what the CC is? Ill give you a clue its not cricket club.

Please enlighten me I'm think it stands for Critics Club?

Before the cc engineers would compare notes in public which usually exposed their lack of knowledge.
The cc saves them that embarrassment now.

The line they tow is that its keeps technical advice from being given to the diyer.

If that was the case then the sparks would also have a closed forum.
Nuff said.

 

[newbuildinstaller]

Know a few mate that have died cheers, happens to 1 in 3 people at some point. I am actually sorry about your father it was a bit insensitive.

The point I was making you talk big game yet prove nothing.

I actually do believe you could help the OP just annoying that you say you can sort it BUT WONT when you have chosen to sign up to and contribute to a DIY FORUM where the whole point is for pros to help to homeowners.

If you didnt want to help dont post!!!!!!

And no I dont talk my custs through the jobs as they contact my business looking for a professional to do the job. I dont find them on frums looking for DIY advice (not a great business model)

 

[newbuildinstaller]

Well why dont you join the CC then show off you work in there then

Typical response from someone in Lancashire and yes you did win the war of the roses lol.

I take it you know what the CC is? Ill give you a clue its not cricket club.

Please enlighten me I'm think it stands for Critics Club?

Before the cc engineers would compare notes in public which usually exposed their lack of knowledge.
The cc saves them that embarrassment now.

The line they tow is that its keeps technical advice from being given to the diyer.

If that was the case then the sparks would also have a closed forum.
Nuff said.

Ahhhhh they not let you in

 

[fezster]

Alright, lets all relax. I thought I was the one supposed to be getting stressed out by my heating system!

Tbf to James, there's been a lot of suggestions, particularly on the other thread, and im sure the correct answer may be in there. If the answer is changing a setting on the boiler or adjusting a valve, im happy to try it. If its changing out a part or adding something, im incapable of doing it. Given ive already wasted money on solutions which haven't worked already, even if im given the right answer, I want to be sure it will work, and ill still need someone to come and do it. From my perspective, if the guy offering the solution is giving me a guarantee it will work or no fee, I dont see that as a problem. As long as the cost is fair for the work to be done (and within my budget!).

Some more info. Boiler was heating downstairs and cylinder from about 12. Hot water was being used to shower the kids at the same time. I turned heating off at 12.30 to see how long the cylinder takes to heat up. Boiler continued to fire for about 20 mins, modulated right down to barely audible. Flow temp 70 degrees, return creeping up past 60. Then boiler shut down. D2 is set to 5, so anti cycle time in d67 is 2 mins. Boiler has now been short cycling for the last 40 mins.

Ive increased d2 back to 20, but as suggested previously, maybe I need to increase to 60. Once the boiler gets in this state, it doesnt seem to recover. Im guessing I need to allow the return temp to drop sufficiently to allow it to fire up and modulate down past the 50 seconds. Tbh, im disappointed it turned off when it had modulated down.another 10 mins at 70 degrees, I believe cylinder stat would have been satisfied. HW target temp is 60 degrees, roughly 7pm on the megaflow stat.

Boiler still short cycling. Ive set D2 now to 60, d67 showing 8 mins. Any other suggestions? This is a fairly simple case now. Heating is off, HW zone is only one open. Bypass is very hot btw, as said previously, Im sure it partially opens with only HW zone.

UPDATE

Boiler fired after 8 mins. Didnt catch how long it fired for, as was typing on here. But return was 51 in d41. Boiler quickly went up to flow temp of 70, return then rose fairly rapidly to 63. Flow showed 73. Boiler turned off. Given anti cycling timr cannot be increased further, not sure what else I can do.

UPDATE 2

Boiler fired for 49 seconds before switching off. So looks like doesnt have sufficient time to modulate down.

UPDATE 3

Adjusted d1 (pump overrun) to 10 mins, previously 5. See if it dissipates more heat.

 

[DP]

cap off the pipe work using those fittings, some flux, solder and heat,

JB how do you solder with water in pipe? Perhaps I am missing something as even a drained off system invariable will still be 'wet' making soldering a difficult task

 

[Steelmasons]

When a customer came to me and said that he had the following issues:
- Ground floor htg, 1st Floor htg and 2nd Floor htg never worked when on together.
- Extension had all rad valves turned off and doors closed to the house as rads never got warm.
- 1st & 2nd Floor htg worked ok on it's own.
- Ground floor heating worked ok on it's own (if rads in extension were still turned off).
I carried out a site survey and ascertained that the above was true, the boiler was a Grant Vortex Pro 15/26, DHW cylinder was 210litres unvented indirect. The boiler was 12m away from the cylinder and the controls. The heat loads were:
- Ground Floor htg, 16kW
- Extension htg, 7kW
- 1st and 2nd Floor htg total, 26kW
- DHW cylinder primary coil, 23kW

I told the customer that he didn't need a new boiler and that he could also keep the boiler set at a max heat input of 23kW. I gave him a price for the works to which he agreed as I gave my word that if it didn't improve the system, he had nothing to pay. Once the work was done 2 years ago, he had (and still has) sufficient heat on all zones inc hot water and straight away he opened up the extension as it could be used for the first time in winter since it was built. This customer has had me back to do various other works at his property and has recommended me to others.

They're the only facts you'll get from me steelmasons. I am not going to back them up with photos of the work as I know people on here will benefit from my hard work over the years, leaving me with nothing to show.

I fail to see the point of this post as you have not revealed the diagnosis.

maybe all it took was a wave of your magic wand??????

 

[fezster]

ALEC1,

I tried vaillant again today, spoke to their installer helpline. The guy was adamant he knows nothing about a new PCB, and was miffed as to how to solve this given that thr boiler is behaving as it should, but that the cylinder absorption was too low as its nearly upto temperature. He did say a pcb change, if there was one, sounded like what was needed, as opposed to anything particularly wrong with thr setup. Could you drop me a pm with details of anybody at vaillant who knows about the new PCB? I have an engineer coming out tomorrow as it seems to be a necessary first step to initiate a dialogue with them.

Many thanks.

As an aside, setting the target flow temp on the boiler to 80 degrees seems to help. This will be to the detriment of efficiency on central heating though. Im thinking a vr65 may help here. If anyone has a setup where they can set the target temp of a non vaillant indirect cylinder independently of ch temp, please let me know.

 

[fezster]

Vaillant engineer came out today. Was a nice guy. I told him about the blog and the updated PCB. He admitted he hadn't heard of it, but said it's quite well known the larger 400 series boilers ramp up the flow temp too fast. He said it's quite possible an updated PCB may have resolved this. Anyway, to my surprise, he said he'll just swap out the PCB for a new one.

Results are unconfirmed as yet. As said previously, the boiler short cycling was more to do with the boiler temp not being sufficiently higher than the cylinder stat. Setting to 75 degrees has resolved this. Cylinder stat switches off with boiler return temp hitting 68 degrees.

On the plus side, I used the calcs that D_Hailsham did from my previous (15 page!) thread and worked out from the boiler manual that with internal resistance and my index circuit, my pump should be able to cope with 5.5m head at 32KW and a 20 degree temp differential. Previously this has not been possible at anything above 26KW because the boiler was ramping up the temperature too quickly in the first 30 odd seconds. However, I've tried it at 30KW, and so far it seems to be ok. I'm not certain this is down to the new PCB, but the boiler definitely seems to ramp up more slowly. No longer an aircraft engine on first fire. I'll run it like this for a while, but if I see any S53's, I may need to range rate lower again. On a cold system, the temperature differential reaches almost 30 degrees, before the return temp starts to rise, which seems quite close to the cut off for an S53 occurring.

The engineer did indicate that ideally my pipework would have consisted of a lot more 28mm before reducing to 22mm. Currently approx 7m of 28mm pipework, which then reduces to 22mm. That's 7m for upstairs zone and 7m for downstairs zone.

 

[D_Hailsham]

The engineer did indicate that ideally my pipework would have consisted of a lot more 28mm before reducing to 22mm. Currently approx 7m of 28mm pipework, which then reduces to 22mm. That's 7m for upstairs zone and 7m for downstairs zone.

The engineer was probably thinking of a system running with a 10/11C differential, where the flow rate/velocity, and consequently pipe resistance, would be much higher. My calculations did not reveal any problems.

 

[fezster]

Thank you for confirming that.

A question - if the system is working fine at 30kw in the current climate (and by fine, I mean not giving me s53. Ignore the rads heating up sufficiently or not for this question), is it safe to assume it will also continue to work if the outside temperature is below zero?

My concern here is that from a cold system, the return temp is around 15, but on a much colder day, it may be a lot lower. Will this make any difference, or will the flow temp track the return temp by the same differential on first fire? Hope that makes sense.

 

[ALEC1]

With the new PCB the target flow temp will be related to the return temperature and the boiler should ramp up slower...that has an efficiency gain too..