Building Regs and replacing vented cylinder with Heat Bank

[megawatt]

If you want a simpler solution in the interim (not perfect but more efficient than where you are now) ...

Open fully all the TRV's on the rooms you use a lot and leave the TRV's set at the desired temperature on all the others then regulate the house temperature by the boiler thermostat.

GXV is a great solution ... Instant heat on demand and efficient boiler performance.

As others have said ... No need to involve LBC

MW

 

[doitall]

Rip it all out and spend your money on a nice Combi instead

 

[Dan Robinson]

 

[SumoAl]

Think I covered that in my first post...

You did, thank you. It just sounded a little vague and I wasn't sure if that was lack of knowedge coming through or just style. Sorry, should have done a better background check before doubting you. My bad.

My two CM systems work beuatifully - CMZone on the rads, CM67NG on the underfloor; which as it happens, also also a plinth heater connected in series on the return.

Boiler doesn't cylcle that much at all (then it does work as a kind of heat bank I suppose).

Do you have multiple CM67Z units on it? I currently have 7 zones using four CM67Z controllers all of which are using the inbuilt thermometer to drive radiators or the plinth heater as well as having the second zone radiators.

When I came to bind them to the HC60NG it didn't work as expected, could it be that I'm missing a system timing master causing these problems? If I run through the binding process again and note down what happens and post could you confirm it's as it should be?

When I put it in beginning of last year I hunted around for help but couldn't find anybody else using it. Called Honeywell but they were not much help either, maybe because I wasn't an installer but DIYing a product that is aimed at the DIY market?

Rip it all out and spend your money on a nice Combi instead

umm, thanks ..... but I'll pass if you don't mind.

Actually maybe a PowerMax in the airing cupboard would solve my problems, or there again maybe not. Had one of those in my last house (new build in 1997 or there abouts), and that put me off thermal stores totally. It couldn't supply hot water if the heating circuit was running so I had to remember to turn the heating off at least 10 minutes before running a bath or else it would be cold. Hopefully a HX driven heat bank is better than that! I did like the way the radiators were driven independently of the boiler though.

Thanks all for your help. Need to think this through some more before spending any money.

 

[croydoncorgi]

Dunno where you are in UKbut there's a company on the South Coast called Sensible Heat which has considerable experience of the Honeywell CM product range. 01273 475834

 

[Dan Robinson]

My setup consist of two HC60NG units:

One for the CM67NG which runs the underfloor heating circuit which is connected to a zone regulation unit - the return to the boiler from this goes back down to the kitchen to feed the plinth heater. I put this in to warm the quarry tiles in the kitchen and lower the return temperature for the boiler.

The second 60NG is feeding the CMZone system. This feeds 5 rads (I only have a small house see). The key difference here is that my boiler does have the effect of a heat bank for low output heat systems as the hot water section is recharged constantly, and is also weather compensated - so the flow and return temperatures are usually quite low.

 

[Dan Robinson]

Doh! double post.

 

[simond]

We fit the larger Hometronic controlled systems with Sensible Heat using HR80 valves and I am not aware of any cycling problem.

So you can end up with the situation where the HR80UK (TRV motor unit) has the trv valve partially open with short demand (say 5 of 20 minutes). Because most of the water goes through the bypass and not through the radiator circuit it means that the (quite long) run between boiler and the airing cupboard which houses all of the valves heats up and just abouts manages to start to heat the radiator when it gets turned off for 15 minutes

I do not understand the reference to all of the valves being in the airing cupboard. What are they doing in there? And what turns off the valve on the radiator? The thermister in the HR80 is meant to stay calling for heat until satisfied, through the CM Zone controller.

And how will a thermal store solve any of this? I suggest the core problem eg: radiator not warming room before turning off, is solved, a heatstore will do nothing useful here.

I suspect it's a Drivel posting too. My reasoning, it's another thermal store justification story, and the CM Zone description does not sound like someone who actually has one.

 

[Doctor Drivel]

I suspect it's a Drivel posting too.

I only replied, read back. I never read properly and thought he may have TRVs all around.

 

[Doctor Drivel]

And how will a thermal store solve any of this?

He is after a buffer to stop boiler cycling. A heat bank gives many advantages, so he may as well go that route and solve many problems and enhance all at once.

 

[Dan Robinson]

But with the control system Sumo has there is no need for the boiler to short cycle. There is simply no point installing a heat bank for the sake of it.

 

[SumoAl]

The buffer zone you have will be helping a lot, that's the kind of effect I'm looking to put into place. Had I a bit more room I would be thinking of a small buffer tank for the heating system only, but not having that room the heat bank is the next step.

For all of the not so good things about the Powermax CPSU I had in my last house (new build in 1997) it would have run the CMZone system I currently have with no problems. It had a standard Grundfos 15-50 in it so I could have swapped that out for an Alpha and had it running very well.

Major downside was that it didn't have any hot water priority and as a thermal store (as opposed to a heat bank) the transfer rate between the primary store and the mains water was poor when the store temperature was low such as when the heating was running.

 

[SumoAl]

OK, the situation is this, I appear to be caught up in some internal politics on this site with some DD making up posts to justify heat banks. Never mind.

A little more about the system then.

The house is a bungalow with a loft conversion, no heating in the loft conversion rooms as so far they haven't needed it in 18 months we have lived here.

Boiler is off in the utility room which is actually just the back half of the internal garage that has been plumbed in. Airing cupboard is in the middle of the house and there is a 30 foot run from the boiler to the airing cupboard (including the up and down bits - the pipework runs between the attic joists).

All of the S-Plan controls are in the airing cupboard including the pump and the automatic bypass, the central heating flow and return pipes go into the floor of the airing cupboard.

So for heat to get to a radiator it has to go

• from the boiler up into the attic space
  pass the vent/feed pipes (which are about 4 feet apart at the moment)
  carry on across attic
  down into the airing cupboard
  Grundfos 15-50 then bypass then split
  
  one leg goes into DHW tank coil, out, through 2 port valve and then becomes the start of the boiler return
  
  other leg goes through 2 port valve, manual gate valve and then into the floor as central heating flow, round raidators and then up through the floor of the airing cupboard and joins onto the pipe from the DHW tank and off to the boiler again

One of the problems is that there are two parts to the central heating, the new and the old. The previous occupants redid quite a bit of the CH plumbing when they moved the boiler out to the garage (kitchen moved rooms as well so boiler had to move) but they didn't do the pipework going to the dining room or kitchen as they are in conrete floors. The dining room is the old kitchen and the current kitchen was the old utility area so they have hard floors where the rest of the house has floor boards (planks not sheets). Digging up the floor int he dining room and kitchen would be the proper solution, but that's just not going to happen at the moment.

In order to get hot water into the old part the lockshield valves on the new areas are very slightly open, about a 1/4 turn from closed at most. This is probably the root cause of my problems and why the CMZone isn't working as well as expected.

I have only one feed and return going off into the floor though so I can't split it into two at the moment, one though I had was that I could have two CH pumps driven from the heat bank for these two different loads.

I still don't understand why people don't think that the HC60NG boiler control won't cycle when used with a CM67Z and HR80UK. The CM67Z specifically has a cycles per hour setting and it modulates by the on time within that cycle.

Anything else I can do to show you people that this is actually a valid question and that I do need your help as opposed to DD yanking your chain again (which I can only guess is something that is suspected from the above posts).

 

[SumoAl]

I suspect it's a Drivel posting too.

I only replied, read back. I never read properly and thought he may have TRVs all around.

I have Honeywell TRV bodies with HR80UK motor units all round apart from the kitchen which has a 2 port valve controlled by a CM67Z and a HC60NG bound to zone one with the CM67Z using it's internal thermister for control of the HC60NG.

Because in effect every radiator is a zone in itself I have removed the S plan motor head for the central heating zone and left the valve open. I've wired in the HC60NG boiler control directly to boiler demand.

At the moment I've also removed the HR80UK from the towel radiator in the en-suite and opened the valve manaully. This means the towel raidator is warmed when there is hot water demand.

 

[SumoAl]

Sorry, lots of posts but just trying to explain as best I can where I am in case something which I left off so far triggers something...

We fit the larger Hometronic controlled systems with Sensible Heat using HR80 valves and I am not aware of any cycling problem.

I do not understand the reference to all of the valves being in the airing cupboard. What are they doing in there? And what turns off the valve on the radiator? The thermister in the HR80 is meant to stay calling for heat until satisfied, through the CM Zone controller.

I think that the issue is the proportional nature of the demand, it appears to demand a proportion of heat if it only needs a bit so it tries to keep the room temperature stable. So as the temperature falls overnight it will get into the proportional band, this means it will call for a little heat which may result in the HC60NG being on for a few minutes every 20minute cycle.

And how will a thermal store solve any of this? I suggest the core problem eg: radiator not warming room before turning off, is solved, a heatstore will do nothing useful here.

See my posting above re the two parts of the central heating, from this thread I'm beginning to understand that I may have to attack that problem before doing anything else as putting in a heat bank is only going to move the problem not solve it.

I suspect it's a Drivel posting too. My reasoning, it's another thermal store justification story, and the CM Zone description does not sound like someone who actually has one.

Or maybe someone who has one but set up very wrong! Doing a Google on "HR80UK" or "CM67Z" doesn't pick up much other than people selling them. Not much comentary from people who have set up multi-CM67Z setups and how they have it working.

I'm off to rebind all the CM67Z units with the HC60NG boiler control and see what happens, from memory last time it didn't go as per the manual, but then there isn't much in any of the manuals about multiple CM67Z units and one being a system timing master.

[lots of time here]

Right, rebound the CM67Z units with the boiler control HC60NG. I have four CM67Z, A, B, C and D using the little stickers they come with.

A has the Sn (System Timing Master) as 1, all the others have it at 0.

If I bind A first it gives me an error, troubleshooting guide tells me it's because I've bound a timing master when no other bindings are present. Ok, good clue there.

So I reset it (15s push) and started again.

Bound B, C, D then A, it all appears happy.

Now, do I need to set the cycle rate parameter on all of the CM67Z units, I've currently got them all set to 3 cycles per hour with a 5 minute minimum on time, so I assume that's not hurting anything.


[and a bit more time]

I had everything but the kitchen off and turned on the heating using the +1hr button on the timer. It took a while for heat to make it's way through to the kitchen and I had to turn the bypass all the way shut to really get something through which will mean that boiler flow wouldn't be good so didn't do that for long.

Opened the dining room and that warmed up, but not that quick which kind of points to low flow as with just the two on and nothing else it should have warmed up fairly quickly.

Turned on another radiator in the house manually and opened the lockshield a bit and the kitchen went cold almost straight away.

I'm now thinking I need to flush the system through rather than looking at a heat bank. Maybe it's just not running well because of the lockshields having to be so shut because of the old pipework.

Would have someone in to look at it but getting someone to return a phone call isn't easy at the moment, so I can only assume that either every heating person is on holiday or there's lots of work out there and this isn't big enough a job.