Non-modulating condensing boilers?

[Egremont]

At one point I was looking at putting the boiler in an odd spot and the waste-pipe flue would have made it just about the only choice, but this never came to pass

Egremont.

[Andy Hall]

Fine. However, you are always the person who promotes stores being able to be smaller because the water temperature is higher. You can't have it both ways as has been demonstrated many times.

Next time the Albion rep. comes in, ask him to explain it to you.

Rubbish. There are no problems with TRVs at this level.

Your understanding of heat storage and distribution is quite limited, isn't it....

If you drive radiators directly from a modulating boiler, when the heat requirement for the space is above the minimum boiler output, the boiler runs continuously. At the lower end, it also runs highly efficiently.

When the heat requirement is at or below the minimum output level, the room thermostat will also play a part and will lock out the boiler until heat is next required. Any switching of the boiler will be on a very long interval, just as it is with a store. However, since this is occuring at a much lower power level than happens when driving a store, there is less energy waste at the time the boiler fires up. It will also be working directly in its most efficient temperature range.

Ask one of the boiler reps to explain this to you. Actually don't - call their technical department.

Perhaps you should use decent ones.

Some TRV4s please.

Plumbers merchants seem to be full of people behind the counter who spout about this or that in an "authoritative" way. Either they heard it from several heating guys who came in or were told by the manufacturer's rep as he was telling them about the latest promo trip to Eyebyeza. When are you going?

[Doctor Drivel]

A store can be many things. You can combine the outout of boiler and the thermal store, moreso a heat bank than store, to improve DHW performace using a smaller storage vessel. You can promote greater condensing efficiency by lowering the store temperature and having alarger store, or a store matched to suit, etc.

You can.

You require by-passes and a control interlock, which can be a bit involved, if you want TRVs on all rads. Taking the rad circuits from the store you can have TRVs on all rads, by only having a Grundfos Alpha on the circuit. You can have two CH zones directly off the store both with just an Alpha pump and TRVs on all rads.

It is 110%. Just read and take note. You don't have to understand. Just accept it.

When having two zones and TRVs on all rads complexities arise. 3kW is the least you will get from a boiler and those boilers are "very" expensive.

Using two CH zones off a thermal store using TRVs all around doesn't even require a room stat. Simple, by just instaling an Alpha pump.

By inserting an outside weather compensator that dictates the temperature of the stored CH water in the thermla store, a condensing boiler operates to max efficiency. Simple to do.

Most have never heard of a thermal store, never mind how you apply it.

You just don't know.

[Andy Hall]

We've been around that one before. There is a short term effect with this which is dependent on the storage volume, the boiler capacity and the rate of use of heat. It does not improve performance in the sense of flow rate, and if used to make a worthwhile reduction in cylinder size, the stored energy may well run out reducing the performance and water temperature substantially - in effect creating a combi. Not a very interesting solution.

Condensing efficiency is improved by operating the boiler at a lower temperature not by increasing the size of the store. The effect of the latter is only to reduce cycling and is only important when, as is required with a store, the boiler runs at high temperature. That argument is more applicable to non-condensing boilers which are designed to run at high temperatures.

It's behind you.

The need for bypasses or not depends purely on the boiler and even if an external one is required, it is trivial. Likewise, control interlock in the form of a room thermostat is also trivial for those of average intelligence or above.

This is pointless. A modulating condensing boiler can do this directly. Several have pump speed control as well so that the boiler burn rate, water flow rate and temperatures can all be optimised for maximum condensing efficiency and lack of cycling. Adding a store in the middle defeats that and is pointless for space heating applications.

Is that what the rep told you? He's a nice guy, isn't he? Don't forget to up that order for the Yorkshire fittings that he needs this month, will you....

There are several that will modulate down to low levels and will drive the radiators directly perfectly well. If your idea were so beneficial, it would be common practice and boilers would be designed to do it. As it is, they are optimised to heat cylinders (or stores) quickly for hot water purposes and to drive radiators directly. That is the main point of arranging for them to modulate. The vast majority do modulate, and very few are around that have fixed output, simply because a store is not the best way to implement a space heating solution unless other energy sources are being added in.

If you do that and reduce the temperature in the store, it is no longer optimal for heating the water. Considering that with a modulating boiler, the temperatures can be run as low as 45/25 degrees to the radiators, the store is going to be pretty useless for heating the water.

Presumably they have in your branch now though?

[Doctor Drivel]

Short term effect? What a BS term! This one is full of it.

What is he on about.

This one hasn't a clue. You size the boiler output and then size the cylinder to support, to attain the level of DHW flow and volume required.

If the store is at a lower temp the stored energy is less. You size to suit.

Nonsense.

Nonsense.

Another thing to go wrong and wreck your boiler.

A room stat cuts off the whole system or zone. Having TRVs on all rads and and Alpha pump, all off a store has no drawbacks.

If you want TRVs on all rads with a boiler directly heating that rads, the control interlock becomes more complex and not standard. A major drawback.

There is no central wall room stat to lmock ooff the zone. What is warm in one room maybe cold in another.

Without a room stat? It can but complexity arises, and the control interlock and by-pass. The thermals store/Alpha pump is by far the best solution.

All added complexity which can be avoided by using a thermal store.

Utter nonsense.

A few and are "very" expensive and highly complex. With a thermal store a cheap simple boiler can be used to better effect.

Sinmple boilesr are there and can do it. Main pressure water is far superior to tanks in lofts in performance. Yet if it was so good we would all be using it. Obvious. Yet even today new homes in estates are being built with low pressure tanks in the lofts. Why? Beats me. Most plumbers don't even know how thermal stores work.

But, Gledhill Thermal Stores are making headway in the new build sector.

They are designed for the replacement market, which is now the largest sector.

No. It is to mate onto an existing system.

As indicated to you the store is the best way. Simpler, more effective, and all rooms can have "fully" independent temp control. On warm up the rads are hot instantly.

I think you mean DHW. You only have the lower CH section controlled by the compensator. The upper DHW section can be 70, 75, 80C. The upper and lower sectionnwill be at too very different temperatures, with the lower controlled by the outside waether compensator. This lower CH section could be as low as 35C and the boiler operates in a low temperature high efficient environment. A cheap simple boiler too, no compe expensive mother...

See just above, re: DHW.

..Lord Hall wears a top hat, this is so ..Lord Hall thinks the top hat is all the go ..Lord Hall wears the top hat all the week ..and the dead mouse upon his lip don't half reak ..he doesn't know it's there as dead mice don't squeak

[Andy Hall]

There may well be a British Standard covering this area.

You are obfuscating again.

Obviously, but there is a lower reasonable limit. One needs to have the store temperature at 60 degrees to produce hot water at a reasonable temperature.

No it isn't. Cycling at high temperature implies far more loss of energy than it does at lower temperatures.

Nope.

Tripe.

The drawback is putting the store in the middle of the control system forcing the boiler to operate outside its optimal range for space heating as well as for DHW.

Rubbish. This is entirely the standard implementation used in millions of homes. TRVs on all radiators except one located in the room with room thermostat.

Surely you are not trying to claim that room thermostats are complex are you? Ask the Danfoss rep. to explain how they work next time he's in.

You are spouting nonsense as has already been explained.

It is no more added complexity to have a pump which is controlled by the boiler electronics vs. an external Alpha. The Alpha is useful for cases where the boiler is incapable of stepped or proportional control of the pump. In cases where the boiler electronics can control the pump - e.g. the Celsius and Micromat among others then it makes sense to use it.

In effect what you are suggesting is an arrangement where you disable the designed control system of the boiler by putting a store between it and the load that it can so easily control, to run the boiler outside of its optimal range of temperature and then to attempt to redress the issue by fitting an Alpha, which good though it is, only operates based on detecting flow/pressure and not under control of the boiler, which also knows aout temperature and optimisation of that.

It's a dumb idea.

Yes it is utter nonsense unless you are trying to introduce energy from another source.

There is a burner, a heat exchanger, a board of electronics, a fan, a gas valve and perhaps a pump. This is not "highly complex" any more than any decent quality modulating boiler.

As long as the boiler is a non-condensing one, possibly.

Provided that the water supply is adequate.

You must be a plumber on the side then, as well as working in a merchant.

Radiators are radiators. If the radiator system is designed to have been run from a conventional 82/70 boiler, then at certain times of the year, high temperatures will be needed. If it sized to give more output and work with 70/50 from a condensing boiler then fine as well and it will be more efficient. Either way a modulating boiler is beneficial if it is condensing.

It isn't simpler because you are adding a store, pump and controls.

The key thing is the radiator output in proportion to that required to address the heat loss of the room. Since many boilers have high peak outputs anyway, what you describe is at best a second order effect.

This is waffle.

Unless you split the store into discrete and separate sections or have two stores, you can't achieve any accuracy of control, especially as you only have one source of heat into the store.

[Doctor Drivel]

A BS covering BS? Mmmmm

Quite clear.

Nonsense.

Nonsense. The store is a great neutral point asset. The boiler work can work at very low temperatures when a weather compensator is attached to the CH section. This also reduces boiler cycling too. A great assset.

You can't read. I said "TRVs on all rads", not one left open that switches the system off when some rooms are calling for heat. Silly idea.

With a boiler directly heating rads if all rads have TRVs, complexity arises to ensure the boiler has flow though it at all times. A thermal store using Alpha pumps eliminates this complexity.

You lack comprehension. There is complexity using a thermals store, an Alpha pumps and TRVs on all rads. No room stat required, no by-pass no flow switches, none of any of that. Alpha are also quiet in operation as they vary the speed.

Much more needless complexity.

You have a boiler without a complicated control system. Simpler, cheaper, longer lasting and more reliable.

The boiler runs at the temperatures dicted by the buiklding load dictated by a weather compensator. The compensator heats the stored water in te CH section of the store.

The Alpha does not have to be under the control of the boiler. It is better separated from the boiler totally and run from a thermal store.

Optimisation of temperature is best done via a weather compensator, not the boiler.

You haven't a clue.

Nope. A condesning boiler is fully optimised.

Not a plumber. No drains and gutters.

If directly attached to an existing system.

No zone valves, just simple pumps.

The TRVs do that. Independent room control "in all rooms"

More BS.

Read again. You can move your lips.

The store can be split into two temperature zone with the same cylidner, both temp zones heated via the same heat souces.

..Lord Hall doesn't know, a man who has no clue ..he has no clue about the things which are known to me and you

..24/7 he is vacant in his head ..no knoweldge, reason, logic, this must be said

..drivel and babble just comes so ..relentless, incoherrent in its flow

..it's time take no notice of this hot head babbling fool ..just laugh and smile and thank the Lord you are sane and cool

[Andy Hall]

I thought so.

Where do you get these lines?

It's a neutral point asset *perhaps* if there is a requirement to introduce heat from solar etc.

Waffle. You know full well that this only does anything worthwhile if there were separate heating and DHW stores. Since the former is pointless anyway, the whole thing goes full circle to where we came in.

As you very well know, the radiator in the room without TRV is adjusted such that the rooms with TRVs are satisfied for heat before the thermostat turns off.

Ask the rep to help you with this one.

The whole thing is pointless and unnecessary in the first place, so adding self adjusting pumps is a separate issue. If a bypass is required, it can easily be implemented anyway.

yes I know.

So what.

I know. I have one, but not for that application

Ask the rep to explain to you about system boilers.

There are loads of extra discrete components in your scheme and a bunch of compromises that make no sense when a modulating condensing boiler is used.

A pump is a pump whether it is fitted inside a boiler or outside. The extra thermostats, relays, switches, pumps and other paraphernalia are superfluous if the system is designed as the boiler manufacturers intended and not as a Heath Robinson project like you are suggesting.

Really? How does it manage to do that? They are normally a sensor on the wall outside plus some electronics. Are you running pipes to the outside wall now?

It is designed to be standalone and for certain applications is useful. However, having flow rate controlled by the same controller as the boiler firing rate and temperatures will by definition be a superior solution simply because the control systems are closed loop and not disassociated as you are suggesting.

Optimisation of temperature is best done with an outside temperature sensor connected directly to the boiler electronics and taken into account by them when directly controlling the pump and burn rate. This also optimises efficiency.

.

Yes, to drive a space heating load directly.

Ah. Probably best. Hard to cut with a junior hacksaw.

Even if attached to a newly designed system with larger heat emitters.

"simple" pumps. Alpha. Hmm...

Exactly. That's why I highlighted the error of your ways.

There is very little splitting possible because the water will naturally convect and form a single temperature gradient.

This was first form physics in grammar school or in my case already covered in the penultimate year of primary school.

[Doctor Drivel]

From brilliant knowledge and experience.

Then there is the boioer interlock.

No by-pass, which could go wrong and wreck your boioer, with thermal store.

Then you should use it on a thermal store.

Few components. It is simple and highly effective, reliable and efficient.

No compromises whatsoever. All aspects: CH, DHW and Boiler are optimised.

No need for such complexity when thermal store is used. Modulating boilers in themselves are compromises.

Some modulates to system pressure - Alpha.

This is utterly pathetic, bending your system to suit the whims of a boiler manufacturer. A designer has control of a system using a thermal store. The store a neutral point at the centre of the system. The boiler is heat source, that is all. The one aspect of the system can be optimised fro the rads which also optimises the boiler performance - by using a weather compensator.

Controlling a cheap simple boiler

In this is it brilliant and ideal and no need for a boiler to be involved.

Not a superior solution. The weather compensator decides the rads flow temperature and then ensures a store of water is at that temperature. A simple boiler is used to heat the stored water to the desired temperature, maintain the boiler at optimum operating condition for efficiency, which also eliminates boiler cycling. The mass of water ensures this. The boilers is on full flow all the time as no rads with thermo valves to close down the flow. Always at the right optimised temp for the system.

Not so. Best is have a mass of water at the correct temperature for the rads dictated by the outside weather compensator. This eliminates:

- boiler cycling totally.

- boiler interlocks

- by-passes

- room stats that control a system or heating zone

Promotes:

- efficient optimum boiler operation, always operating at the lowest temperature set by the weather compensator

- independent room temperature control, not overriden by overall system temperature control

- quiet CH zone operation

- instant heat at rads

- Instant DHW

- few overall part

- no complex parts, apart from weather compensator, which is not complex by todays stadards.

- simple parts: simple boiler, simple thermo rad valves simple pumps

- elmimation of troublesome parts

- etc

- etc.

Simple and self contained. Just treated as any other pump.

Nonsense. Distinct tem,temperature zone scan be maintained.

..Lord Hall doesn't know, a man who has no clue ..he has no clue about the things which are known to me and you

..24/7 he is vacant in his head ..no knoweldge, reason, logic, this must be said

..drivel and babble just comes so ..relentless, incoherrent in its flow

..it's time take no notice of this hot head babbling fool ..just laugh and smile and thank the Lord you are sane and cool

[Andy Hall]

Now you really are scratching around.

Do you have a dud batch that you are trying to return to the manufacturer or something?

Not with your arrangement.

Everything's a compromise. Defeating control systems unnecessarily is pointless.

Sigh......

Who knows how to correctly match his heat source and control system to a standard load.

You are attempting to gild a lily and painting it with s**te instead.

That depends on the boiler. If it's one of the budget range that you sell because you get free trips to Eyebyeza then quite possibly.

If it's a decent quality one with integral controlled pump, conrolled modulating burner and weather compensation then it is a great deal more.

I am surprised that you even tried that one. Actually, no I'm not.

Waffle.

Complete waffle. What desired temperature? You still haven't explained how you propose to optimise for the maximum efficiency of the boiler (low temperatures), the requirement for the store to be at high temperature for DHW production and the needs of space heating (variable to match the weather conditions.

You can't achieve all of these objectives with a single store. Two would be required and then the boiler would still be run non optimally for space heating.

No it doesn't.

No it doesn't

Irrelevant.

Big deal.

No it doesn't unless two stores are used and even then the boiler does not have the opportunity to modulate down to most optimum rate during space heating because the control is defeated.

Achievable whatever.

Achievable whatever

Second order effect on rate of rise in room temperature

Achievable in many other ways as well and a store is a good way for this part, just not for space heating with this type of boiler.

highly debatable

No complex parts either way.

the discussion is about a modulating boiler not a conventional non condensing one.

Even you (actually especially you) can't defy physics.

You cannot control a temperature gradient in a single body of water in two separate and discrete entities which is what you are suggesting here. It will naturally convect to form a single one.

If you wanted to tap off at a certain point on a cylinder to get a lower temperature or deliver a lower temperature in a fixed way, that is reasonable.

However, you have been suggesting that the needs of DHW production (80 degree storage) and spae heating with weather compensated temperature control of the stored water is possible in a single vessel. It very obviously isn't

[Doctor Drivel]

Not at all. Also they open up and defeat the object of a condensing boiler and greatly raise the return temperature.

It is clear you are very silly

..Lord Hall doesn't know, a man who has no clue ..he has no clue about the things which are known to me and you

..24/7 he is vacant in his head ..no knoweldge, reason, logic, this must be said

..drivel and babble just comes so ..relentless, incoherrent in its flow

..it's time take no notice of this hot head babbling fool ..just laugh and smile and thank the Lord you are sane and cool

[Andy Hall]

You know very well that an ABV is set to only open when the circuit flows are stopped entirely.

Ask the rep to explain it to you.

A tub of Boss White please.

[Doctor Drivel]

The hall rad is balanced it may not pass enough flow for the boiler, so the by-pass opens. Best avoid a by-pass and use a thermal store/heat bank and an Alpha pump.

.."self abuse"! Lord Hall doth shout ..he heavily indudges, of this no doubt ..of this act he does hanker ..that's why his mates call him the DIY wanker

[Andy Hall]

Don't be silly. This is a non issue.

1) There is nothing that says that the radiator in the hall has to be used as the non-TRV one nor that it would be of a size where there is insufficient flow.

2) It is perfectly possible to choose living room or other locations as the non-TRV location.

3) TRVs do not close off completely until the room temperature is above the set point. They close off gradually with temperature and reduce the flow first. In order to make sure that the temperatures in rooms with TRV achieve a desired level, the TRVs are set to make sure that that happens close to when the room thermostat becomes satisfied.

I know that you are clutching at straws, but it is more typical to use hemp, not straw in combination with Boss White for thread sealing.

A plastic pipe cutter and three lengths of 15mm barrier tube please...

[Rick]

For a Thermal Store - you are right it is far better to turn off modulation - you can do this by a simple removal of a bridge on most boilers.

I have a Baxi 100HE/Barcelona just pull out one bridge to turn off modulation, and also pull 2nd bridge to put in in high power mode.

most boilers are the same.