To fit or not a secondary heating circulation pump

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Hi All,

Just had my new heating system installed comprising of:

Vaillant Ecotec 630 plus system boiler
Vaillant Unistor 210ltr unvented cylinder with 18ltr expansion vessel
Vaillant 360f programmer
VR65 wiring centre
VR10 cylinder probe
Magnaclean fitted on return under the boiler

All up and running, system power flushed and also flushed raditor by radiator (lots of hitting bottom of rads with a mallet), all (18) radiators then balanced. All rads bar two towel rails are fitted with TRV's. The system has also be installed as an 'S' plan with two MV's (one controlling heating side the other the DHW).

All is working, and I must say the DHW is fantastic, plenty on tap, powerful & hot.

The concern I have is related to the heating side of things - basically, most of my 18 rads are being fed from a 22m main heating circuit with long lengths of 15mm copper pipe runs, reducing down to 10mm by the time the connect up to most rads.

My concern with this is that it seems to take a lengthy time to see an increase in heating temps say from 18 degrees to 22 degrees (this 4 degree increase can take several hours to achieve even though the heating is set to full power and no DHW is being called for at the time - so heating is getting the full boiler output whilst trying to increase the temp up).

My heating engineer suggest that this may be due to teh long 15mm & 10mm radiator feeds restricting the heating flow somewhat. He has sugegsted two options these being:

Renew entire house pipework to all rads with wider bore piping (this is really not an option due to costs & mess it will make of the house)

Or fit a secondry heating circulation pump (Grundfos Alpha 2 15/60) on the heating side next to the heating two port MV and wired into the VR65 with the heating MV so they work together?)

My question to all of this is - would the above secondary circulation pump improve the heating-up times ie; due to more pump flow & get the hot water to the rads quicker & with more force - or would it make little/no difference?

Additionally would fitting this extra heating pump cause any conflicts/problems with the boiler pump.

Appreciate your thoughts on the above extra pump questions.

Thanks
 
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The "engineer" is looking for work. :rolleyes:

The pump in these boilers has several modes. Has the "engineer" tried the different modes?

The boiler has an adjustable automatic bypass valve. Has it been set properly?

What is the difference between flow and return temperatures? it should be 20°C (Flow = d.40, Return = d.41)

At 20°C differential a 15mm pipe can carry about 18kW maximum. I doubt if any of your radiators are that size. :LOL: 22mm will carry 40kW.

You say the system has TRVs on all radiators except two and that the radiators have been balanced. Was this done with the TRV head on or off?
Did the balancer do it by feel or using thermometers?

Do you know the total output of your radiators? It might be worth comparing that to the output of your boiler.
 
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Thanks Mr Hailsham for your reply....I'll answer what I can now until I get home to check the flow & return temps.

The pump mode has been changed from factory setting 2 to setting 0 - see below:

d.19 Only in ecoTEC plus:
Operating modes of the two-speed heating pump
0 = pre ignition speed 1, hot water or heating speed 2, overrun speed
1
1 = pre ignition speed 1, hot water speed 2, heating speed 1, overrun
speed 1
2 = like 1, but speed in heating mode dependent on heating part load
d. 0 (if d.0 is below 60% of full load, then pump speed 1, otherwise
speed 2)
3 = always speed 2
(factory setting: 2)



The auto bypass settings I'm unsure if this was altered.

The TRV heads were removed whilst balancing took place - and balanced by hand/feel.

The heating surveyor whilst measuring the rads etc calcualted a heating output across all 18 rads of some 25KW (some big doubles in the mix) + 3KW for hot water = 28KW

Does this help for now? - what happens if there isn't a 20 degree flow & return temp differential....let's say it's less until I check - what impact will this have on the heating performance?

Cheers
 
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so you have an old system with a new boiler,cylinder and fittings.i was asked to comment on a similar installation only to find it a converted church,high god like ceilings.
 
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set d19 to 3. don't bother with the additional pump, set the 360f to analogue and set the ch flow temp to max. if you have a autobypass valve external to the boiler close the internal bypass. this will improve things
 
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just to reiterate, don't fit another pump, your boiler will get upset :(
 
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Thanks dangermouse -

I've changed the boiler pump setting to (3) meaning always speed 2

I've set the rad dial temp on the boiler to max (75 degrees)

Current flow temp is 75 and return is showing as 60....so 15 degree differential.

There is no auto bypass fitted other than what's in the ecotec boiler - not sure what I'm meant to alter with this so as yet I've not touched it.

The 360f has been set to analogue.....not sure what this change makes...can you explain?

Will see what all these changes make to the heating performance for a day - but still pondering what the drawback or benefits of a secondary circulation pump may have on this setup...can't see whay it should conflict with teh boiler given the way it could be wired-up....anyone care to expand & explain this further for me....don't wish to shell out 250 quid if I'll see no real benefit/difference.

thanks so far....anymore thoughts welcomed...maybe gas4you could pass comment given his extensive vaillant knowledge.

Cheers
 
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simplest of questions to answer: follow M.I.

Ah I see now...manufacturers instructions....I'v read throuh these page by page....can't find anything that says 'do not fit a secondary circulation pump to heating circuit' nor a clear explanation of what is the best suited boiler pump speed for my particular system set-up....nor does it clearly explain why the 360f should be set to analogue....nor does it say I should set my boiler heating temp to max......Whilst it does mention all of the above are alterable, it doesn't really tell me what effect changes made to any will do & what they should be set to for my system.

That's why I've come here seeking opinions from subject matter experts who have seen/faced & overcome most if not all of what I'm describing....so please do keep these coming on this post so I can understand, learn & hopefully resolve my concerns.

many thanks
 
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seems i missed a vital bit of information:

just had new heating system installed

in that case it is even easier; you pay, at least my clients do, to get a new PROPERLY WORKING heating system.

if the installer makes a mistake in the design, or choice of boiler, or the way it is installed, then it is his problem.

i would strongly advise against doing anything yourself, just get him back to sort it out. don't even make suggestion as he can then turn around and say: you wanted me to do this.

let's face it, if you paid for a new lump in your car, and it would not go over 50, you would not try to fix it yourself would you?
 
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seems i missed a vital bit of information:

just had new heating system installed

in that case it is even easier; you pay, at least my clients do, to get a new PROPERLY WORKING heating system.

if the installer makes a mistake in the design, or choice of boiler, or the way it is installed, then it is his problem.

i would strongly advise against doing anything yourself, just get him back to sort it out. don't even make suggestion as he can then turn around and say: you wanted me to do this.

let's face it, if you paid for a new lump in your car, and it would not go over 50, you would not try to fix it yourself would you?


I see what you are driving at....whilst in principle agree with your approach - technically the installers have done everything as specified in the orginal heating quotation & by the book - so because I'm not entirely satisified with the overall heating performance ( and not the result of their workmanship), is it more of a case that my expectations should be better managed...or is it that the installers propose alternative/additional solutions that may ultimately attain my staisfaction level, which in their opinion would fall outside of the original quote spec & therefore either cost me additional monies to resolve or leave me with an option to resolve it myself.
 
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technically the installers have done everything as specified in the original heating quotation & by the book
It all depends on what you asked the installers to do. If you just said "I need a new boiler" and left him to specify what he would install and you accepted his proposal, which then proves to be inadequate for heating the house, then you have no one to blame but yourself. But if you said "I need a boiler which will be capable of heating all rooms to 21°C from cold within half an hour", and the boiler fails to meet your requirements, then the fault lies with the installer.

However, whatever was requested, a competent installer would have looked at the existing system, realised there might be a problem, and taken this into account when specifying the boiler.

As to the suggestion that the pipework needs replacing, this proposal is ludicrous. The system just needs balancing properly.

Just for information, what was the old boiler?
 
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