Flow Rate Reqd for Thermal Store/Heat Store

[Balenza]

simond wrote

If the customer wants a significant flow rate and you have downgraded the heat bank to 65C it will lose temperature quickly and deliver low water temp HW.

All depends on the storage capacity and the cylinder stat setting for replenishment and of course the size of the Hex .

The Nu Heat unit has no automatic variable cold mix valve

What is an automatic variable cold mix valve if I may ask?
Do you mean a TMV ?.

and no varispeed pump, so it has little chance of masking the side effects of a low water storage temperature that you advocate when significant flow rates are demanded of it. The cold mix will remain unchanged at the output.

Once you drop the storage temperature to safer levels then no singing and dancing elaborate temperature controls are needed in my view.
If the maximum storage temp is 60 then a PHE is not going to deliver a higher temperature than this no matter how low the flow through it on the secondary side.

 

[Doctor Drivel]

Its not a case of how much heat the Danfoss HEs can extract. It's how much energy you have in the heat store for them to extract.

It is educate him again time... here we go again...

You are right in a way but missed lots out so wrong.

1. A boiler, say with a delta T of 22C, set to deliver water into the top of the store at 70C - never less.

2. A high efficient plate heat exchanger (it is clear you have never heard of double pass plates)

3. A store calculated so the size is more than adequate to deliver enough DHW at a store temp of 65C.

The above three points deliver and return low temperatures for condensing operation the vast majority of the boiler runs time.

Also, have the pipework configured so that the boilers input to the store is pumped directly into the plate when DHW is called - this combines the output of the boiler and the store. There could be a timer, say set to 30 to 45 secs to bring in the boiler whether the stores stats are calling for heat or not. The timer stops nuisance firing when sinks and basins are used. This reduces the store size substantially.

Now, say, thank you Dr Drivel I never knew all that and I will stop making prat of myself.

If the customer wants a significant flow rate and you have downgraded the heat bank to 65C it will lose temperature quickly and deliver low water temp HW. That's why you've mentioned a properly sized store - it would have be very large to have a chance of coping at this low temperature.

Look at the double pass plates and combining the boiler and store energies. See above.

And I'm still waiting to hear about the 4 bar unvented system

Please use a telephone and read specs. Hint look at ACV tank-in-tanks that go up to 10 bar and others.

Now bow your head in shame for your lack of knowledge, and most of all being unable to figure out something so easy.

 

[Doctor Drivel]

Once you drop the storage temperature to safer levels then no singing and dancing elaborate temperature controls are needed in my view.
If the maximum storage temp is 60 then a PHE is not going to deliver a higher temperature than this no matter how low the flow through it on the secondary side.

Good point Balenza! It simplifies the whole setup. A well sized store, well sized condensing boiler and adequate anti-stratification baffles will give a simple, reliable and efficient heat bank indeed.

 

[simond]

I am aware of the ACV products as discussed earlier. However, this is not a specific unvented cylinder, it is a hybrid product suitable for vented or unvented use. I accept your point though.

The Heatstore you arrogantly discuss is not the Nu Heat unit you blithely recommended but your ideal design. You require 70C. The Nu Heat does not pump directly into the HE and does not have a lag timer on demand. And the sizing is a moot point because you are running on small margins to get a high flow rate out at 60C without destabilising the store. Interestingly, I am not aware of any commercial manufacturer currently producing a heatstore to your 'ideal' design. Why do you think that is?

Ironically, the ACV would be a much better solution to the problem and is not a heatstore. It will also need G3 to connect it up. Why do you not recommend them, when they are simpler, smaller and have a self cleaning HE?

 

[Doctor Drivel]

Its not a case of how much heat the Danfoss HEs can extract. It's how much energy you have in the heat store for them to extract.

You didn't read what was written did you? Such a low attention span

If the customer wants a significant flow rate and you have downgraded the heat bank to 65C it will lose temperature quickly and deliver low water temp HW. That's why you've mentioned a properly sized store - it would have be very large to have a chance of coping at this low temperature.

Nope. Larger however not gigantic. Also combining the boiler and store energies out[puts means probably no, or not much larger.

The Nu Heat unit has no automatic variable cold mix valve and no varispeed pump, so it has little chance of masking the side effects of a low water storage temperature that you advocate when significant flow rates are demanded of it. The cold mix will remain unchanged at the output.

I think I know what you are on about. But no anyway.

This really is a suggestion built on sand.

You still can't comprehend.

And I'm still waiting to hear about the 4 bar unvented system - and don't tell me I can make my own, I know that.

Please read what was written.

 

[Doctor Drivel]

The Heatstore you arrogantly discuss is not the Nu Heat unit you blithely recommended but your ideal design.

A design I have implemented and works great. I used a Danfoss 3-way valve with remote temp sensor. It was on the pump after the plate with one port pumping into the cylinder and the other back just before the plate. It pumped around the plate and opened up just to allow enough heat into the plate to maintain the DHW flow temp. This acted as a variable speed pump would and would only return to the cylinder water that needed to be returned not destroying stratification.

You require 70C. The Nu Heat does not pump directly into the HE

It does, it has DHW plate pump.

and does not have a lag timer on demand.

True, but one can be fitted though.

And the sizing is a moot point because you are running on small margins to get a high flow rate out at 60C without destabilising the store.

The DHW pump van be used as a shunt pump to maintain the whole store at 60C. Some Gledhills do this. The ACV Heatmaster has one too.

Interestingly, I am not aware of any commercial manufacturer currently producing a heatstore to your 'ideal' design. Why do you think that is?

Send them my way.

Ironically, the ACV would be a much better solution to the problem and is not a heatstore. It will also need G3 to connect it up. Why do you not recommend them, when they are simpler, smaller and have a self cleaning HE?

The tank-in-tanks are hybrid unvented cylinders/thermal stores. Look at the specs. The outer section can supply the CH. The outer section is also heated by a boiler too. The inner tank is an unvented cylinder. Can be vented. May as well have a cheaper plate heat x instead. NU Heat put the plate inside the store ensuring grater efficiency and response at the taps.

 

[Balenza]

simond wrote

Interestingly, I am not aware of any commercial manufacturer currently producing a heatstore to your 'ideal' design.

I know a few manufacturers of TS systems which have much lower primary temperatures than 60-65c to deal with, so its nothing new.

Why do you think that is?

Because your not fully aware of the systems available and have a limited knowledge with thermal storage systems.

And the sizing is a moot point because you are running on small margins to get a high flow rate out at 60C without destabilising the store.

You certainly post your fair share of rubbish on this forum.

 

[Agile]

Water Systems (Dr Drivel) on the

Who is Water Systems?

Not only does he not tell the truth about thermal store operating temperatures but he does not even admit who he is!

If he were telling the truth then he could post under his own real name instead of making up all these stupid false ones!

Tony

 

[Softus]

Water Systems (Dr Drivel)

Who is Water Systems?

The last forum member who lied so blatantly even claimed that he'd driven 240,000 miles in one year.

Water Systems could legitimately claim that he's drivelled that far.

 

[gas4you]

C'mon softus, you're the man let him have it

 

[Softus]

C'mon softus, you're the man let him have it

I can't possibly do any better than Water Systems is doing to himself.

 

[gas4you]

 

[Doctor Drivel]

Why is this site frequented by mentalists?

 

[Doctor Drivel]

Water Systems (Dr Drivel)

Who is Water Systems?

The last forum member who lied so blatantly even claimed that he'd driven 240,000 miles in one year.

Was he a pilot? A mini cab driver?

 

[Doctor Drivel]

Water Systems (Dr Drivel) on the

Who is Water Systems?

Not only does he not tell the truth about thermal store operating temperatures

Does he say that they operate at 30C?