Any plumbers here? Pics included, please help me identify whats what :-(

[Jez]

Hi,

Edit: TLDR: Tank of water is nice and hot and as such the heating sources are not firing much, but the water out of the taps is luke warm (but pressure is fine).

I appreciate these pictures look a mess, the pipework doesnt mean a lot to me, but i am hoping that it may look simple to someone on these fine forums who actually has a clue about hot water systems!

I am not actually sure what type of system this house has, is it unvented? When turning off the cold mains supply all water trickles to a halt including the hot taps, after a little initial surge?

The issue we currently seem to have is that water is only coming out luke warm, almost too cold to shower, this happened suddenly one day, and i have no idea why. The immersion heater works fine, has a new stat, and upon pulling the stat out it is boiling hot and therefore not firing much. The whole tank feels very nice and warm so i know this is heating. The immersion isnt kicking in much (it fizzes when it does - always has) compared with before this happened, its almost like hot water isnt being drawn off the tank and is somehow being diluted with cold. As i say the immersion has a new stat, and the tank feels just as warm as ever, but it is firing noticably less which my layman diagnosis has put down to hot water not exiting the tank?

So i know the top tank with internal float does the central (radiator) heating header, i know this as caused a leak before in our heating circuit and this emptied out

So this is where i dont know what the heck is going on. I figure that the electrical white & grey item above the immersion is the boilers temp sensor to call for heat (this isnt firing much since the issue, as the tank is already hot). The red pump i think is the boiler heating loop pump? (the boiler is downstairs - kerosene fired). The rest of it i have no clue about, the silver thing, the other silver thing, and what seem like piped with a million junctions.

I basically dont know how to even start resolving this luke warm water issue. If i leave the boiler switched off and use the immersion only (what we usually do, kerosene is a pain) its hardly firing, the tank feels really warm, but we run a hot tap receiving luke warm water for over 10mins solid, and the immersion barely kicks in and its stat still feels boiling hot as it should if removed from the slot in the heater.

 

[Jez]

Many Thanks for the replies so far

Ok, so i get the motorised valve, and it appears to be OK and oprates automatically (i can hear it turning as expected when i play with the system.

What i cannot understand is why the output from the system is only luke warm, with only occasional heating kicking in

 

[Jez]

Ok so thats what that thing is?

Why does it mix cold water in with the hot water at all? I just want the contents of the tank?

This is probably a stupid question, but i didnt ever claim to know anything about this

 

[Jez]

I think the issue has to be the tank end, as all taps and outlets around the whole house are the same luke warm temperature. (3 bathrooms + kitchen taps)

What i dont get about the blockage idea, is the pressure being fine even with a normal tap set to full hot

No work has been done on this since we bought this house, or for many years before that looking at the state of it all

 

[Jez]

Haha mine looks quite simple compared with that lot!

 

[Jez]

This is just what i needed, thankyou very much for explaining what some of the pipework is doing and the function of it I now at least can see where the hot and cold are coming and going.

That tap was stuck HARD, but i just got it with a large pair of grips. If i turn it right down i get freezing water out of the taps, and if i turn it right up i am getting boiling (steam coming off) hot water, the heating elements also kick in as i would expect when i run it boiling hot like this - HURRAH!

This unfortunately leads me to the next question (even though i am very glad to have some hot water now!), the flow from having it full hot is very low.

This leads me to wonder: Is there perhaps a new partial blockage out of the tank before that tap? This combined with the low flow from full hot on that tap, and the sudden dip in tap temperature?

 

[Jez]

No (wet) underfloor heating no, the cylinder just does the radiator central heating, and the hot water.

That tap definitely adjust the water temp, if i feel the pipes going in and out of it it matches exactly as per the_dead_parrot's advice and reflects in the water coming out of the taps.

Why it is there....i am not quite sure, you guys tell me I realise it does give an element of control (i can choose my water temp from it), but i can also do that from the immersion stat, and on the boiler control unit itself (the tank temperature).

 

[Jez]

Would this help you have hot water for longer? If you set it fully open and set your desired temp on the thermostat you will have the capacity of the tanks worth of hot water.

If you have the tank hotter and set to mix then your hot water would last longer. I.e if you had a 10l tank but set it 50% hotter than you wanted and set the mixer to 50% would you effectively end up with 15l of water at the desired temp?

Oh that is a very good point, i guess this is a design feature. Sadly my hot flow isnt good enough at the moment to turn the mixer down at all

Is the flow directly proportional to the temperature of the water, i.e. when the water is set to freezing is it coming out of the outlets at mains flow?

If so can you turn it until the flow is the optimal balance of fast and hot? Gravity hot water is always awful, should be better at the downstairs taps though...is it?

Its not a gravity system, its pressurised with the cold incomer, so in theory its all at the same pressure all of the time. If i turn off the cold mains to the house the hot also stops at the same time. The tank is also only on the 1st floor, it flows both up a floor to the 2nd floor and down a floor to the ground floor at the same pressure from the tank

But yeah the flow right now is directly proportional like you say, if i turn it right down i get the expected mains cold pressure from the hot taps. This is what leads me to think there has to be a partial blockage stopping hot water hitting the hot side of the tank mixer at full flow? The tank itself is at mains pressure, so both hot and cold at the mixer should in theory be identical.

Does my diagnosis make sense?

 

[Jez]

If the flow from all taps is poor then I can only presume there is a blockage around the tank area.
.

Got to be this surely? My water is pretty hard so i do get scale everywhere, and my tank is set to the hottest temp possible.

See my theory about a blockage from the pressurised tank to the tank mixer, it has to be this surely? Nothing else makes sense. The blockage cannot be after the mixer or in any other pipework, as turning it to full cold i get full cold pressure from the hot taps.

 

[Jez]

My next question

How do i drain this tank? The drain valve at the bottom doesnt release any water, i am guessing this is due to me turning off the mains and there being no way for air to get into the tank?

Or something?

I really want to change the immersion heater element as it looks ancient and is bound to go soon, and i want to take that bit of pipe off to the mixer to see if it is blocked.

 

[Jez]

The top tank doesnt seem connected to the main one? It seems to be creating a head for the radiator system? As i say that top tank drained completely out when i created a leak in the radiator system and sat dry for a couple of months until i fixed it and let it fill back up. This didnt affect the hot water system in any way? I was not expecting the top tank to drain if i drain the hot water tank....

The hot water tank itself is clearly mains pressurised, you can visibly see the hot flow stop at the same time as the cold when you turn off the cold incomer to the house. The hot also flows up a floor from that tank as the tank is situated on the central floor of the house.

 

[Jez]

Yep, it didnt seem to drain

I need to try it again. Perhaps my drain valve is chalked up.