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Who's right ? (Read 2446 times)
CWatters
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Re: Who's right ?
Reply #12 - Jan 8th, 2018, 4:49pm
 
I'm late to the party but it seems odd to me to have a heat store heating a hot water cylinder. Normally you would just have a coil in or heat exchanger on the heat store to heat DHW.



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thescruff
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Re: Who's right ?
Reply #11 - Jan 7th, 2018, 9:18pm
 
In your 2nd drawing you show a red pipe heading back to the store and a pink pipe going I assume the heating.

Where it has been modified the pump looks to connect to the red pipe.

Is the red pipe now the flow and where does each end go.

What happened to the pink pipe and where did it go.
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Re: Who's right ?
Reply #10 - Jan 7th, 2018, 9:16am
 
thescruff wrote on Jan 6th, 2018, 8:59pm:
Yes I know that but the store return and heating return have to be at least common somewhere in the circuit


Not sure what you mean by the 'store return'.  I have two separate heat exchanger coils inside the heat store.  One of them comes from the oil boiler which heats up the water.  The other feeds the ch/hw circuit
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Re: Who's right ?
Reply #9 - Jan 6th, 2018, 9:03pm
 
Can you pencil a sketch and add flow arrows and id the pipes
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thescruff
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Re: Who's right ?
Reply #8 - Jan 6th, 2018, 8:59pm
 
Yes I know that but the store return and heating return have to be at least common somewhere in the circuit
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Re: Who's right ?
Reply #7 - Jan 6th, 2018, 4:53pm
 
The heat store is the only way back.  Just think of it as a central heating boiler.
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Re: Who's right ?
Reply #6 - Jan 6th, 2018, 10:15am
 
Yes, I realise that, but it looks like the store circuit is the easy way back.

It had an MV before so there was some control on it and assume that is still the case, but is there a valve on the return you can adjust, To balance the circuit a bit
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Re: Who's right ?
Reply #5 - Jan 6th, 2018, 8:06am
 
The heat store provides the heat so can't be taken out of the equation!  Not a new system but an existing one. Just that he's changed things a bit!

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Re: Who's right ?
Reply #4 - Jan 5th, 2018, 9:10pm
 
One other thing you should try is holding a bottle of water under the vent pipe and get someone to turn the pumps on and off.

I only wish you had asked an opinion about sludge buckets, (thermal stores) I don't think you would have gone for it.

Insulation in unheated spaces is critical to any system.

If you getting air that can't be removed it hasn't been installed correctly.
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Re: Who's right ?
Reply #3 - Jan 5th, 2018, 9:03pm
 
Is there a lockshield valve on the store return because it looks as though that circuit would pinch the lions share of the flow.

Have/can you try the heating only without the store being on.

Trying to understand it is difficult and certainly, I would say a likely problem as he's restricted the heating flow ( I think)
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Re: Who's right ?
Reply #2 - Jan 5th, 2018, 4:43pm
 
My drawings are lousy!  Just think of the flow as coming from the heat store (Akvaterm) then up that vertical red arrow, down the pink arrow to the hw cylinder area. There it goes to the pump and after the pump the usual split CH/HW with two motorised Honeywell valves.  The fuzzy grey line is the CH feed after the Honeywell valve and it connects into the original CH system flow halfway down.

It's a tad academic now as he came round yesterday and he and his son spent a good 3-4 hours getting rid of the air in the system. Involving hosepipes and suction pumps. This air was partially blocking the return...once it was out of the way the whole system sprung to life with good heat in all radiators.  

We had the heat loss discussion. I came at it by describing a system where there was 500 yards of copper pipe between heat store and the first rad. Eventually he agreed with me. But we then had the further discussion about the discussions we'd had at the outset. There were the three options - as he reminded me.

Option A - keep the pump at the heat store and run two pipes down to it to create the neutral point. Trouble was that given all the steel etc in the building getting a clean run back - especially for the vent pipe that needed a gradual upward slope - was nigh on impossible.

Option B - the one we went for. Move the pump up to the area of the HW tank (where the feed and vent pipes were), make the tweaks to the circuit as outlined above. The option we went for. What I am a bit annoyed about is that he didn't point out to me the implications re heat loss in the changed circuit - especially as it was he who suggested the use of the heat store to run the boiler fully in condensing mode etc. This heat loss may mean that I can't run the boiler as efficiently as I wanted to and I've wasted all that money. Time will tell. He suggested that with the improved flow rate that it might not be as bad as it was. Fingers crossed.

Had I known about the heat loss then I guess I could have tried a bit harder to find a way to go the Option A route. Hard call. I do know that I tried damn hard the first time round (it was possible pump noise that was the driver as LOML has the hearing of a barn owl).

Option C - a pressurised system. Which, as previously mentioned, was ruled out due to unknown existing pipework provenance. We shall see...may have to bite the bullet and go for it downline.


That was yesterday and all tickety boo.  Then today I needed to turn the pump off.  When I turned it back on, the old symptoms came back so there is clearly still air in the return.  Bit bloody annoying as we had good heat from upstairs and downstairs rads but now downstairs are cold and upstairs tepid at best.  

Anyway, if you're still with us (!) back to that heat loss.  If I got a pump with a faster flow rate then the water wouldn't lose as much heat?  Yes?  No ?
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Re: Who's right ?
Reply #1 - Jan 5th, 2018, 1:39am
 
Crikey my head hurts reading that  Huh

Can you do a better line drawing showing the connections from the cylinder to the pump and then the rads.

You mention heat store a few times, is it a cylinder or thermal store (make and model) please.
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Who's right ?
Jan 4th, 2018, 12:12pm
 

Can someone please confirm that I am correct in my thinking ?

The first photo is a rough drawing of how the CH layout used to work.  The pump was located in the garage by the heat store. The pump fed a metre into the house where the feed split to two motorised valves.  One valve sent the hot water down a dedicated pipe to the hot water cylinder.   The second valve fed the CH feed and about another metre after this valve it split to feed the upstairs rads and downstairs rads.  Within feet of where the split occurred, this feed pipe was hitting the radiators that it was designed to feed.  Assuming that the system was reasonably balanced then my argument is that the temperature in this feed pipe is going to be roughly that when it left the heat store...give or take the odd degree.

...

NB the diagram does not show the CH split to the downstairs rads.

Now when my plumber put in the new boiler he was very fixated on neutral points and insisted that the pump be relocated up at the hot water tank and the feed and vent pipes connected there to create the neutral point.  However this meant that the motorised valves needed to be located here as well which in turn necessitated modifications to the primary hot water feed.

The two original valves were removed and the T between HW and rads removed.  The feed to the rads was cut off and blocked.  The original and remaining feed to the HW tank became the main feed to the new pumps' location.  Two new valves after the pump...the one we're interested in...the CH rad one then feeding a new pipe that T'd in part way down the upstairs original CH feed run.

...

With this new arrangement, I am 11 degrees of heat lower at the pump then that leaving the heat store because of the long run now built in to the system due to the new layout.  66 degrees leaving the heat store (don't worry about whether this is high enough etc for the purposes of this discussion) and 55 degrees when it hits the actual CH upstairs rad circuit.  My plumber does not accept this. He says that I'd see the same thing on the original system which I think is bonkers.  Original system...distance between heat store and first rad ...4m.  New system...distance about 30m.

A pressurised system was and is out of the question as there was existing inaccessible pipework underneath the floorboards with joints of unknown provenance and as I'd already discovered one joint that wasn't properly soldered, I think this decision is sound.

Supplementary question.  The furthest radiators from the CH feed point are in the kitchen.  With every other radiator and HW tank off, the hottest temperature of the incoming CH water to these rads is a meagre 36 degrees.  Is this an indication of an under-powered pump or a blockage in the old pipework ?

Second supplementary question.  My plumber says that you get different temperature readings if the pipe is vertical or horizontal.  EG horizontal copper pipe coming to a 90 degree feeding the vertical pipe into the radiator tail. Doesn't make sense to me.


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