Replacing hot water tank with combi boiler?

1984ReturnsForReal_2

mikey72 wrote: »

Vaillant ecotec 837 or 838 may be ok, depending on your water supply.

Combi is definitely the most sensible way forward with 1 electric shower.

1984ReturnsForReal_2

MobileSaver wrote: »

There's already two water tanks up there

Forgot to say.

One of them is a feed & expansion tank for your central heating. Its mostly water but the rest is poisonous.

ziggyman99

1984ReturnsForReal wrote: »

Because the hot water tank needs to be below its feed otherwise it wont vent & the water in the system will find its level (because its a gravity system) which basically means the hot water flowing back into the cold water cistern.

The ONLY way of doing it would be to raise your cold water feed cistern to a height 1.5 meters (for vent pipe) above the hot water cylinder which would be above most peoples roofs sitting externally above on the tiles.

Were do you get this figure of 1.5m from? I'm sorry your wrong. a combi tank has it's feed tank built-in and would work fine. You can even get a combination tank were the header is split into 2 (called "D" tanks) so you could get rid of the heating feed and expansion tank.

1984ReturnsForReal_2

ziggyman99 wrote: »

Were do you get this figure of 1.5m from? I'm sorry your wrong. a combi tank has it's feed tank built-in and would work fine. You can even get a combination tank were the header is split into 2 (called "D" tanks) so you could get rid of the heating feed and expansion tank.

Cant remember where I got 1.5m from, checking now.

I know you can get combination tanks & get rid of the cisterns but is it going to feed two showers & a bath & a washing machine & dishwasher, toilet etc?



Edit: I remember now.... It was something to do with that baby who was scolded to death in its cot. Because hot water was venting into the cold cistern & melted it. Maybe it was 750mm (or 450mm) vent over the cistern, either way. Its cylinder + cistern + vent pipe height.

ziggyman99

The cistern on the combi tank only feeds the hot water. The big cold water tank would continue to supply cold water i.e. toilets, bath and sink. Your washing machine and dishwasher are fed directly from the mains and usually cold fill only these days. It still may struggle to supply hot water but that's not a call I can make from this post. There are many factors to be taken into consideration. I cited a combi tank as a possible alternative to a combi boiler. There are other alternatives. An unvented cylinder or a storage combi boiler for instance. If I was asked by my customer to provide a solution I would explore all possibilities.

The baby that scolded to death was killed because the cold water tank was incorrectly supported. The thermostat failed on the immersion heater causing it to boil and fill the cold water tank with hot water. Because the tank wasn't supported correctly it sagged and split causing 40/50 gallons of boiling water to cascade through the ceiling. Nothing to do with combi tanks....


1.5m, 750mm, 450mm...... I think your just guessing now..;)
The vent pipe is supposed to vent into the cold water tank, that's why it's called a vent pipe.

The 450mm refers to the height of the vent pipe on a central heating feed and expansion tank. That is to help stop pump over.

ziggyman99

1984ReturnsForReal wrote: »

Forgot to say.

One of them is a feed & expansion tank for your central heating. Its mostly water but the rest is poisonous.

I apologise for continually shooting you down but your wrong again.
It isn't poisonous. It's water, iron oxide (rust) and inhibitor. Nothing poisonous there. They would not allow a poison to circulate through a coil in a hot water tank in case the coil split. That would result in poison being available on tap! Not good.

I'm not being funny or anything but should you post if you don't know the facts?

noodlepie

This is a confusing thread.
Is it about a combi boiler or a combination cylinder?

1984ReturnsForReal_2

ziggyman99 wrote: »

The cistern on the combi tank only feeds the hot water. The big cold water tank would continue to supply cold water i.e. toilets, bath and sink. Your washing machine and dishwasher are fed directly from the mains and usually cold fill only these days. It still may struggle to supply hot water but that's not a call I can make from this post. There are many factors to be taken into consideration. I cited a combi tank as a possible alternative to a combi boiler. There are other alternatives. An unvented cylinder or a storage combi boiler for instance. If I was asked by my customer to provide a solution I would explore all possibilities.

The baby that scolded to death was killed because the cold water tank was incorrectly supported. The thermostat failed on the immersion heater causing it to boil and fill the cold water tank with hot water. Because the tank wasn't supported correctly it sagged and split causing 40/50 gallons of boiling water to cascade through the ceiling. Nothing to do with combi tanks....


1.5m, 750mm, 450mm...... I think your just guessing now..;)
The vent pipe is supposed to vent into the cold water tank, that's why it's called a vent pipe.

The 450mm refers to the height of the vent pipe on a central heating feed and expansion tank. That is to help stop pump over.

You are trying to get out of the fact you cannot put a conventional cylinder in the attic without raising the cold water cistern.

And 450 refers to the offset on cylinders required for the vent pipe.

& the vent pipe must be 150mm + 40mm per meter above the cistern.

And now you are on the subject of putting 2 water systems into the OPs house with the use of a combination cylinder & a cold water cistern for supplying the appliances why don't you just rip out the cistern & supply the appliances with mains water.

You already have his loft with 3 water storage vessels in it & 2 systems. :rotfl:

Let alone the fact you argued about putting his cylinder for his system in the loft without even knowing it wouldn't work.

Keep digging. By the time you find the the full solution your way you are up to 4 vessels in the loft.... Lets just hope it can support the weight.

Serious about the vent pipe over the cold water cistern though. You might want to go & have a read.

1984ReturnsForReal_2

noodlepie wrote: »

This is a confusing thread.
Is it about a combi boiler or a combination cylinder?

Ziggy is just trying to get out of a mistake he made by saying you could put his cylinder in the loft.


Everything else is about a combi-boiler...

1984ReturnsForReal_2

ziggyman99 wrote: »

I apologise for continually shooting you down but your wrong again.
It isn't poisonous. It's water, iron oxide (rust) and inhibitor. Nothing poisonous there. They would not allow a poison to circulate through a coil in a hot water tank in case the coil split. That would result in poison being available on tap! Not good.

I'm not being funny or anything but should you post if you don't know the facts?

Next time (if) you ever go into the loft take a glass up with you & have a drink out of the feed & expansion tank.

Then come back & let us all know how you get on.


Seriously though AGAIN.

You need to have a look at the ingredients lists of cleaner & inhibitor & add in the fact that there is possibly lead (yes lead, you know the solder & flux you can put on radiator pipes) in there & rust.

Hardly non toxic is it?

Some people just don't get it & I guess you are just another one Ziggy.

Good luck drinking from the glass Ziggy, let us know how you are getting on from hospital.


Your still !!!!ed for me catching you out saying that with his system you could put his cylinder in the loft...