Going to take the plunge and get a high efficency gas boiler

07-12-2011 01:25PM

OP, I'm sorry for my part in ruining your tread, it seems to be a common thing now days:o

Plombier · 07-12-2011 02:14PM

What heinbloed is suggesting,

a. Installing a timer with the boiler.

Imagine leaving your car engine running all day just in case you might need to drive it, my car uses 1 litre per hour to idle wasted energy so I turn it off!!
As we speak the interlock technology is built into some newer cars the engine shuts down when it comes to a halt.

b. A radiator installed which is always open (frequently the bathroom radiator is chosen for this) or the installation of TRVs which allow for a fixed minimum draw. The smallest thermal consumer (radiator, buffer tank) determines the boiler's minimum outlet. For example the smallest consumer consumes 2 kW then the boiler has to modulate from 2 kW upwards

To use the energy produced by the boiler and plant heinbloed suggests overheating some or all parts of the building.
Even if the boiler modulates to 2KW this is heat energy that has to be wastefully dissipated in whatever part of the building it is pumped to.
If for example the house at design conditions (-5C) has a heat loss of 10KW, when the temperature outside is at 10C the heat loss from the building is now only 4KW if the boiler modulates down to 2KW its still producing 50% of the energy required to heat the house fully.

Even if we employ a 300ltr buffer tank to try and alleviate the problem, at the boilers minimum output the tank will be heated fully through the heating differential in less than 5mins. So either a much larger buffer tank is needed or a clever control system but if heinbloed can’t see the benefits of a simple boiler interlock then what for the concept of controls??

DGOBS · 07-12-2011 02:23PM

So I will ask them all again, since they were ignore earlier.....all with a ?

With only trvs in control, what happens when the house reaches temperature?
Why heat your water storage tank when you have no requirement for hot water?
Why heat a zone such as sleeping areas during the daytime?
Why heat the living zones of the house when your sleeping?

Regarding parts supply, in EXPERIENCE (of the practical nature) the imported boilers that do no have established agents here result in delays in getting components when required.

Again the only real question in the last post (you seem to have ignored) is when I queried as to how many installations you have installed and commissioned?

Of the ones you have actually had experience working on, what were the measured outcomes, when installed as you have suggested?

You see, aside from work, I love Fomula 1 racing, I could talk for hours about it, the technical aspects, driver programs, tyre wear on particular circuits...etc
But I am fully aware, if I attempted to drive a F1 car or design one, it would be a disaster!

Re TRVs, when the house reaches temperature, the boiler will short cycle and waste fuel as the will be no demand from the emitters, even with the boiler in low fire mode.
TCVs also have no demand link to the boiler, so every time the boiler is on you waste fully heat unrequited water.
Without zoning, areas of the household that do not require heating at that time period will again waste energy once the boiler is firing.

DGOBS · 07-12-2011 03:27PM

thought March can after Christmas, or is that different in your world too?

Unlike some, winter is my busy period, also as I am going there on the manufacturers invite, I would hardly argue with their suggested dates!

You still have not answered regarding the wasted fuel on the system you are suggesting, is it just me, or does everyone here that works daily in this environment seem to disagree with your theories?

On a foot note:
I personally would never be as ignorant to refer to anybodies literacy as you have no idea as to the difficulties a person may have, I find it both rude and offensive. In my work I come into contact with may people on a professional footing and have to deal with their literacy issues.

heinbloed · 07-12-2011 04:22PM

I try it with Plombier's assumptions first, I quote:

To use the energy produced by the boiler and plant heinbloed suggests overheating some or all parts of the building.

That isn't true. A small boiler won't produce more thermal energy than is lost through the fabric. So with a correct choice of components and intellectual input - as demanded by the Irish building regulations - a situation of overheating will never occure.
Prove the opposite.

Even if the boiler modulates to 2KW this is heat energy that has to be wastefully dissipated in whatever part of the building it is pumped to.

A wastage of thermal energy won't occure during the heating season. Outside the heating season the boiler won't be turned on. Since there is always a thermal loss through the fabric there is always no waste of thermal energy created by the operating boiler.
Provide a EN 12831 calculation to prove that this is wrong.

If for example the house at design conditions (-5C) has a heat loss of 10KW, when the temperature outside is at 10C the heat loss from the building is now only 4KW if the boiler modulates down to 2KW its still producing 50% of the energy required to heat the house fully.

I'm not argueing about the chosen units nor about the result in percentage but:

The penny has dropped, well done Plombier !

As long as the thermal loss through the fabric is higher than the minimum output of the radiators/boiler no thermal energy will be wasted by boiler cycling. The boiler will be providing thermal energy through the entire heating season, no cycling. It's as simple as that.

Again: an energy demand calculation according to EN 12831 must be done in all cases. Without such a very basic exercise all rule-of-thumb installations are more or less wasted.

Barack Obama · 07-12-2011 04:51PM

Not sure what's going on but my head is spinning! :eek:

I'm pretty sure that one of the modulators is out for me (especially at the suggested price of over €4k!). I'm going to get a 24k condensing boiler that gives 91% efficiency. Surely this is good enough?

Because this boiler is either on or off, the system surely must be able to tell it when to turn off. If fitting TRVs will not do this then zoning must be the answer? Or is that any other way of turning off the boiler automatically??

To be honest, DGOBS's 4 questions make sense to me...

heinbloed · 07-12-2011 04:54PM

Sorry, DGOBS, I realy took your questions to be of a rethorical nature. But you tought me otherwise, so I give it a try:

1.

With only trvs in control, what happens when the house reaches temperature?

The house won't reach temperature, that is a wrong assumption. The air temperature in the rooms (!) will reach a satisfactory level sooner or later.
And this air will at all times lose thermal energy to the colder walls and windows, will be cooled down by ventilation.
The TRV - which modulates whilest restricting the flow - will close not entirely. A TRV will go closer and closer (in lay men terms) the nearer to the desired demand the room temperature gets.
With the result that the emitted thermal energy from the radiator covers exactly the thermal loss of the air.
Like a modulating boiler the radiator is modulating it's output.

A very simple and clever invention such a TRV, one really has to read the leaflet to understand how a wax filled cartridge influences the valve.

2.

Why heat your water storage tank when you have no requirement for hot water?

I really don't know DGOBS. Read my posting again, your quoting is misleading since incomplete. Please quote entire sentences, this is a good standard in written communication.
If quotes become to long one can use " ...... " to mark a missing/non-quoted part of a text.

Example:

If quotes become ........................ part of a text.

As you can see it is important to quote correctly, otherwise the sense becomes lost.

3.

Why heat a zone such as sleeping areas during the daytime?

If the thermal loss of the room is not covered there is no heating, just a reduction of cooling. Does that make sense to you?
There are TRVs with build-in timer as well. These can be manipulated to zero-throughput when the timer demands that. Read the accompanying leaflet provided by the manufacturer.

4.

Why heat the living zones of the house when your sleeping?

Read the answer to question 3. , the thermal loss of a room not covered by a thermal input is not called heating .

Again the only real question in the last post (you seem to have ignored) is when I queried as to how many installations you have installed and commissioned?

This is an unreal question you are asking here, DGOBS. Read your last post again, I answered it already ( the answer was " Yes " ).
You did not ask for any number.
Concentrate on technical facts. Learn from those who can teach you something. And always trust your own senses, follow logic as available to you.

Of the ones you have actually had experience working on, what were the measured outcomes, when installed as you have suggested?

Since you are not asking any detailed question here (meassuring what? Units ?) I can't answer your question. I simply do not understand it.

heinbloed · 07-12-2011 05:05PM

Barack Obama asks:

I'm pretty sure that one of the modulators is out for me (especially at the suggested price of over €4k!). I'm going to get a 24k condensing boiler that gives 91% efficiency. Surely this is good enough?

A modulating combi condensing boiler running on gas does not have to cost more than € 800-1200.- including VAT.
A 24 k boiler is for the average household in Ireland heavily oversized, half of it would do 90% of all households in my opinion. You must be living in a circus tent (smiley).....
The boiler's minimum efficiency should be 90% or 91%, check this out. That is the legal minimum, not the optimum. Charging for such an 'incompetent' boiler working at the baseline of legality a full €4,000 is a rip-off.

Do you know the thermal energy demand of your house? Maximum demand in kW ?

Barack Obama · 07-12-2011 05:21PM

heinbloed wrote: »

Barack Obama asks:

A modulating combi condensing boiler running on gas does not have to cost more than € 800-1200.- including VAT.
A 24 k boiler is for the average household in Ireland heavily oversized, half of it would do 90% of all households in my opinion. You must be living in a circus tent (smiley).....
The boiler's minimum efficiency should be 90% or 91%, check this out. That is the legal minimum, not the optimum. Charging for such an 'incompetent' boiler working at the baseline of legality a full €4,000 is a rip-off.

Do you know the thermal energy demand of your house? Maximum demand in kW ?

I don;t know those figures but there are some factors -
15 year old detached house so only average insulations
Currently have a 24k Potterton Suprima 80 boiler which is never turned over halfway, and most of the time under a quarter of the way up. Now I understand that this does not lower down the burn it just increases the gap times when boiler is burning.

So, is a 24k boiler maybe too big for my needs? Do they have the control know to lessen the on time like my current boiler? I'll be getting a new timer switch as well so maybe this can do this?

A combi boiler won;t suit because of the distances of some of the bathrooms from the boiler. Also, there is a summer valve to make heating the water in the summertime a little more efficient.

I was quoted €2100 for a new boiler and 12 TRVs to be fitted and tbh I thought that was a good price. But I now see that there has to be some way to switch off the boiler if it's not necessary

Plombier · 07-12-2011 05:26PM

Of course heinbloed’s grammar is perfect.

First of all, DGOBS, mark your questions with a question mark, being literate I find it easier to identify a question even if this question has hardly any structural grammar.

"Writing is an act of faith, not a trick of grammar."
- E. B. White

Weather compensation makes sense where the internal heat load is depending on the time, on the date.
But not where the internal heat load is frequently changing because of changing usage of the structure, because of passive solar gain.

A standard family home with south facing windows and insulated according to building regulations will have no benefit from a weather compensation.

When the sun shines during the cold heating season and is warming the building via the windows the weather compensation unit does not sense this - it is shaded.

When cold sleet and rain hits the facade and causes cooling of the structure the weather compensation unit does not sense this - it is shaded.

If the night is clear or cloudy - the weather compensation unit does not sense this.

When the open fire is running and the kitchen in full swing the weather compensation does not sense this - it is not there but outside, shaded....

Ask a heating engineer about the exact calculations.

Or buy a magnet for the fuel pipe in your car, it's even cheaper.

As you have said yourself at any time during the heating season the building can be above the required set point (without weather compensation to prevent it) and not requiring any energy input, with a boiler turndown of 1:5 the boiler will still output 20% of maximum even there is no requirement.

Now I ask you ??? if this energy will not go wastefully into overheating the building(don’t forget the always open radiators), will you please show us with facts and figures where it end up.

Please show us your figures EN 12831 or whatever method you choose but I ask you for some solid proof not idle hearsay????

Or maybe you bought a magnet for the fuel pipe on your heating.

heinbloed · 07-12-2011 05:43PM

Barack Obama writes :

Currently have a 24k Potterton Suprima 80 boiler which is never turned over halfway, and most of the time under a quarter of the way up. Now I understand that this does not lower down the burn it just increases the gap times when boiler is burning.

"...which is never turned over halfway..." Does that mean your boiler resp. the burner of it is only firing half of the time there is thermal demand from the radiators?

Then this boiler is 100% oversized.

....most of the time under a quarter of the way up.

Then it is 200% oversized. Note below!

Invest a bit into professional knowledge, get a heating engineer in who will do an energy demand calculation for you.

He will tell you as well what type of boiler will suit best to your situation. Pay for this service and get the calculation (according to EN 12831) in writing.

Go for a modulating condensing boiler.

Correction
Above I stated: "Then it is 200% oversized". This is obviously wrong. Correct is: It is 300% oversized.

07-12-2011 05:43PM

Barack Obama wrote: »

I'm going to get a 24k condensing boiler that gives 91% efficiency. Surely this is good enough?

I would say that's perfect;)

Barack Obama wrote: »

Because this boiler is either on or off, the system surely must be able to tell it when to turn off. If fitting TRVs will not do this then zoning must be the answer? Or is that any other way of turning off the boiler automatically??

.

It comes down to whether you let the boiler continue to generate heat when none is required causing it to cycle on and off or fit a device(zoning) to tell the boiler when enough heat has been generated.

07-12-2011 05:58PM

heinbloed wrote: »

I suppose the underlined part is a question, what " they" stands for isn't clear to me, but I give it a try:
Contact ELCO or whoever is there and ask them about sales conditions, about technical back-up. I'm not working for them and can't advise you on this issue. It is the non-idiots (greek term, no insult) who decide what to do and how to proceed.....

Elco do not have a supplier in Ireland or a service network or any parts:)

But yes that do have a CE Mark:D

Barack Obama · 07-12-2011 06:01PM

heinbloed wrote: »

Invest a bit into professional knowledge, get a heating engineer in who will do an energy demand calculation for you.

He will tell you as well what type of boiler will suit best to your situation. Pay for this service and get the calculation (according to EN 12831) in writing.

Go for a modulating condensing boiler.

Correction
Above I stated: "Then it is 200% oversized". This is obviously wrong. Correct is: It is 300% oversized.

Not sure how the boiler can be 300% oversized when only sometimes it is turned up a quarter way and at times (like now) it is turned up half way. If I was to get one a third the size it could not give me the required output!

I would happily go for a modulating condensing boiler if I knew more about them! Do you know of any well used makes\models in Ireland so I can do some research? There seems to be no mention of them on the manufacturer websites that I've looked at. Are they as easy to install and will all registered gas installers know how to install and configure them?

Thanks

Barack Obama · 07-12-2011 06:07PM

gary71 wrote: »

It comes down to whether you let the boiler continue to generate heat when none is required causing it to cycle on and off or fit a device(zoning) to tell the boiler when enough heat has been generated.

My afternoon's research has been looking at the Worcester Bosch TD200 controller and RT10 thermostat

DGOBS · 07-12-2011 06:16PM

Barak, you heads spinning cos as usual there is someone in the room spouting so much rubbish based on what he has rand in books, rather than working practically on heating systems tat are already installed and require upgrading as in as much as possible to conserve energy and save on fuel cost.

In an ideal world on new builds anything is possible

When retro fitting keep it simple, 3 zones if existing plumbing allows, all zones with interlock and thermostatically controlled, preferable stats with set back features especially for sleeping areas, complimented by TRVs on all rads not in rooms with that have the zone stat, couple with a good quality reliable hi efficiency modulating gas

In the words on o e greater than I, don't suffer the fools!

This board has become so bound up in crap from one man, people will soon go elsewhere for sound logical understandable advise, as all good advise become lost in pointless aguement

07-12-2011 06:23PM

Worcester make good stuff as do Viessmann and Valiant. I would want a minimum of 5 years parts and labour warranty.
Heinbloed is right :eek: with the idea of getting your heat requirement worked out so the boiler can be set to match, in the UK any boilers I fitted I would be required to do that calculation send it to the gas registration body and if I'm wrong I lose my registration( no pressure) there isn't anything like that here, but most good installers will fit a boiler and configure correctly without doing a heat load calculation.

DGOBS · 07-12-2011 10:44PM

I don't think any installer here worth their salt would argue that inherently boilers in this country have been over sized, and that a fundamental issue such as this is long overdue a proper regulated approach to ensure boilers are sized correctly.

DGOBS · 07-12-2011 10:44PM

Barack, worchesters CDI boilers are magic

Going to take the plunge and get a high efficency gas boiler

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