Weather compensation & choice of pump

[ALEC1]

there is nothing wrong with them if you install them with on-off controls...a search of the forum shold tell you something though....

 

[p7777m]

The Vaillant system boilers have a narrow modulation range -
The 618 ecoTec plus (which doesn't appear to have a double speed pump) only modulates from 6.7 to 18kw at 80/60C and 7.1 to 19.1kw at 50/30C
The ecoMax 618/2 E does have a double speed pump but has an even narrower range - 11.0 to 18.4 / 11.6 to 19.4 respectively.
The 418 ecoTec plus modulates from 5.0 to 18.6k and 5.3 to 20 respectively.
Am I getting needlessly hung up on modulation range or is this seemingly limited range significant?
Why should the "worse" UK boiler have a wider modulation range?

 

[p7777m]

there is nothing wrong with them if you install them with on-off controls...a search of the forum shold tell you something though....

Are you refering to the number of "why isn't my Vaillant 4** weather compensation/control/etc working" posts?
If so could that be because of the larger proportion of 4** than 6** boilers in the UK, and not necessarily because they're problematical?
Please don't take this the wrong way - I'm not picking an argument here & *really* do appreciate your (and others) comments & help - just trying to get some perspective here

Pete

 

[ALEC1]

low modulation is a benefit to stop short cycling....i agree vaillant dont go that low...but low enough if you match your radiator output to the boiler...

compensation controls tend make the boiler run at low output for as long as possible...so the lower the better...

Atag and broag go lower. something to do with dutch building regs i think

 

[ALEC1]

with out knowing the sales figures we cant say, the 600 series has been about longer than the 400...


you have to have an outdoor sensor in Germany, it makes sense to use what they use in my opinion.

 

[mehran]

p7777m, I am not a valliant boiler geek but from what I understand the 400's have a bit of a design flaw around the flow and return temps.

basically if the the flow and return temp become too far apparent it goes in to lock out. the heat exchanger in valliants are very restrictive so this problem pops up more often than in other makes.

Dont have much to do with valliant other then fixing them. I would recommend Intergas boilers, getting a remeha isense and then connecting a outside sensor to it. if you want you can even use a modulating external pump and wire it into the boiler.


that way you can have a modulating boiler with modulating internal & external controls and modulating pump. you dont have to put up with faults codes from lack of flow and get a (imo) better boiler.

 

[ALEC1]

thats one issue, but the other is microfiring at low load, most boilers work with a low delta t between flow and return, necesary for compensation controls, but the 400 doesnt seem to go below 12c... the result is microfiring.... very wasteful...

 

[David937]

THIS: //www.diynot.com/forums/plumbing/vaillant-ecotec-415.301005/

An issue many have with their Vaillant Ecotec 400 series boilers.

 

[Agile]

there is no research supporting zoning as being effective in saving energy. but where my clients keep records there is plenty to suggest that weather dependency saves energy over switchng boilers on and off

I would be very surprised if you really think that.

If you do then you must be one of those who ( wrongly ) think its best to keep their heating on 24/7

Any heating is just to feed the heat loss of the building. Cutting that out for a few hours in all or just some zones is always going to save energy !



Tony

 

[mickyg]

with out knowing the sales figures we cant say, the 600 series has been about longer than the 400....

says who?? what are you talking about? What can the 600 do what the 400 cant exactly? They both have the same software as far as operating WC and vaillant own controls are concerned. The principle design of the 400 is about 6 yrs older than the ecotec 600/800 series.

 

[mehran]

though I would not go as far as saying what Alec has stated... I can imagine were zones are not thought out well enough it could lead to making the boiler less efficient.

were heat from one zone travels in too another. to maintain the first zone temp you have to increase the flow temp which could lead to moving the boiler out of the condensing range and ending up no better off or even worse off.

 

[mickyg]

my personal opinion if you wanna zone, WC and have a modulating pump just fit a ATAG Q and fill your boots, take away any complications. Vaillant/Glowworm are decent brand, and mostly what i fit but not ideal for multi zoning WC and actually impossible on GW(at least done to any sensible format anyway). Set out your priorities for the system and then maybe choose the boiler or vice versa, as you seem to have decided on everything you want and are now trying to decide how they cobble together, but they wont.

 

[matt1e]

well i think people have to distinguish between weather compensation and weather dependency...the former just running up and down a curve, and the latter be able to operate with no room controls... these two being offered by vaillant and viessman on the 200 and 300 series only...

weather compensation and weather dependency????
lets just call it the same thing eh or an optimised system if you prefer

there is no research supporting zoning as being effective in saving energy. but where my clients keep records there is plenty to suggest that weather dependency saves energy over switchng boilers on and off

first sentence B*ll*cks!, read tonys' (agile) post above, second sentence agreed but its still weather compensation you are on about so please refer to it as such
with respect Alec, I know you are trying to help the op here and as I said earlier "you can get as sophisticated as you like" but sophistication costs, i.e it carrys an initial outlay
the question is... are you going to recover this cost?
in a domestic situation I doubt it
going back to the ops original question

I'm leaning towards having weather compensation, but I'm stuck at choice of pump.
I'd like to go for a Grundfos Alpha - low power consumption and low noise (I assume); also ability for it to adjust speed as appropriate which seems to be appropriate for maximising boiler condensation (please correct me if I am wrong)
But of course I cannot use it in intelligent/autoadjust mode because of the need for overrun when the boiler shuts down. I don't fancy on ordinary bypass as that seems inefficient and an auto-bypass would need something fancy such as an LLH & seperate pump just for this circuit (thanks, Tony, for your earlier comments on this), all of which seems over complex, costly and is simply gaining efficiency in one area by sacrificing it in another)
Which means that I'd need to choose one of the pumps fixed speeds.
Is this entirely consistent with using weather compensation, maximising condensing potential, and minimising cycling?
I'd have thought that ideally the pump speed (maybe together with everything else including boiler modulation etc), should all be controlled by a single control unit; but this doesn't appear to be possible.

maybe I should have replied

of course its possible mate we'll just fit an ***** boiler with weather compensation connected via plc if you need a central controller, the overrun can be handled by the same plc we'll just add another module, add a pressure tranducer to the pipework to drive a VFD (inverter if you must) controlling the pump, we will add another module to operate a proportional valve for bypassing when needed and another module/proportional valve/and sensor for each heating zone then program the plc to spec no probs
that'll be £??????+ VAT... but in your 3 bed semi it's gonna save you at least £?? a year
there is a quote in the ops above post that sums it up

(thanks, Tony, for your earlier comments on this), over complex, costly and is simply gaining efficiency in one area by sacrificing it in another

I dont exactly know what post the above quote is in relation to but its a good point anyway

the point I'm trying to make is any sort of weather compensation is no matter how crude is more desirable and cost effective than no compensation at all

ditto for zoning

sometimes you need two curves... one of my clients wanted the towel rails on in summer, but of course they would not be very warm in summer....(the cylinder reheat was too short with the solar/ part L coil)

you could have zoned them as an additional dhw/heating circuit controlled via trv/pipe sensor/stat/plc etc
but to be fair alex I agree, if It were on the continent an extra "heating zone" such as this would be supported and much easier to deal with

Matt

 

[bell824]

I would be very surprised if you really think that.

If you do then you must be one of those who ( wrongly ) think its best to keep their heating on 24/7

Any heating is just to feed the heat loss of the building. Cutting that out for a few hours in all or just some zones is always going to save energy !



Tony

Now then tony let me get this straight if i allow the heat loss of the building to cool down for a few hours saves me energy during this time (yes i and all would agree with this) BUT that energy is all used up againto reheat the thermal envelope of my house again!! so were exactly is the cost saving? i want my house warm for when i get up in the winter this is before sunrise therefor solar heat wot do it so i have to reheat the framework AGAIN which i let cool down!!

As for the op i would strongly advise against the use of an alpha pump with the 400 series causes to many conflicting interests with temperature readings, normally have to set the alpha to constant output's rather than mosulating as the boiler does not like it.

 

[matt1e]

I would be very surprised if you really think that.

If you do then you must be one of those who ( wrongly ) think its best to keep their heating on 24/7

Any heating is just to feed the heat loss of the building. Cutting that out for a few hours in all or just some zones is always going to save energy !



Tony

Now then tony let me get this straight if i allow the heat loss of the building to cool down for a few hours saves me energy during this time (yes i and all would agree with this) BUT that energy is all used up againto reheat the thermal envelope of my house again!!

Hi bell824
it all depends on the building type,thermal properties/heating type and use

for example, I live in an old georgian four story property
all 4 floors are each a seperate zone
there is only me and my son live here
the top floor gets used if I have guests staying over, maybe 2-3 times a year ( sometimes more but not much more)
the basement houses my studio and a storage room
there is only one rad in the basement it is a large double convector controlled via a local room stat
my studio gets used once a week maybe more sometimes but usually less (as in I might not venture down there for weeks nowadays) and if I have a few people round (a dozon to twenty usual scenario when its used) then the last thing you want is the heating on
so you tell me, what do you think is best? zone the two floors I rarely use off or leave the heating on all the time
each floor is 21ft x 34 ft with 10ft ceilings single glazing and solid walls btw

Matt