One Pipe System Ideal Mexico 2 Boiler

[chloeradhsaw]

Hello friends - I really struggle to understand my heating and hot water system

I posted my question on Diynot but it ended up being five pages and couldnt get to the bottom of it and I thought worth asking the elders on here for their view - Hot water temp is 40 Degrees - Ideal Mexico 2 Boiler - https://www.diynot.com/diy/threads/hot-water-temp-is-40-degrees-ideal-mexico-2-boiler.623404/

Questions
1) Is my system fully pumped or not - It appears I have a pump but then rely on gravity to get water back to boiler for heating and also for hot water. I think this is a hybrid and I dont know the terminology - Many engineers who come here are suprised at it and so am I
2) I do not have hot water even if boiler on max demand after cylinder change - Is it because of the pipe bends or cylinder needing to be gravity coil type? Advice from DIYnot has been add a pump after the two port valve but that seems really strange given it worked before orhave a new cylinder made

Help so much appreciated

What I know
1) Ideal mexico 2 bed 125 heat only boiler - There is one flow pipe (3 inch white bore pipe) and two returns (one return from centra heating and one return from hot water cylinder). There is a DAB 65/135 pump on the boiler which pushes the water upwards
2) Cold water and FandE tanks in loft
3) Only one control for hot water cylinder on system
4) Certain I have a one pipe system

Old cylinder is picture below and new cylinder below - Old cylinder did heat up very nicely but new one does not anymore - No changes to pump speed and 2 port valve in manual mode

Old

New

 

[ShaunCorbs]

Picture of the boiler and pump please ?

 

[chloeradhsaw]

Picture of the boiler and pump please ?
Thank you so much - There is two returns (one more behing boiler from radiators)

 

[ShaunCorbs]

Any more pipes around the boiler (left hand side)?

Easy was to tell if gravity turn heating on pump should run / have power

Turn hot water on inc making a call on the cylinder stat etc pump won’t have power

That cylinder isn’t suitable for gravity heating due to the coil having a high resistance

 

[chloeradhsaw]

Any more pipes around the boiler (left hand side)?

Easy was to tell if gravity turn heating on pump should run / have power

Turn hot water on inc making a call on the cylinder stat etc pump won’t have power

That cylinder isn’t suitable for gravity heating due to the coil having a high resistance

1) There is one more pipe at the back of the boiler which is a raditor return - There is also a gas pipe behind the boiler

2) I always have to turn on heating to get hot water - That is because there is one flow pipe and a two port (which I put in manual mode) to divert to hot water cylider

I am not convinced that I have gravity hot water - I have a pump at the boiler which shoots water up the white flow pipe and that is teed t the hot water cylinder

How can I tell what system i have

 

[ShaunCorbs]

1) There is one more pipe at the back of the boiler which is a raditor return - There is also a gas pipe behind the boiler

2) I always have to turn on heating to get hot water - That is because there is one flow pipe and a two port (which I put in manual mode) to divert to hot water cylider

I am not convinced that I have gravity hot water - I have a pump at the boiler which shoots water up the white flow pipe and that is teed t the hot water cylinder

How can I tell what system i have

Sounds like the wiring has been altered when they installed the two port

The white left pipe in the cylinder cupboard goes to the heating tank doesn’t it ?

 

[chloeradhsaw]

Sounds like the wiring has been altered when they installed the two port

The white left pipe in the cylinder cupboard goes to the heating tank doesn’t it ?

I agree it has been wired wrongly - Thats a small matter though

The white left pipe is 3 inch pipe - This is the main boiler flow - It is teed for the hot water flow and also runs into the loft where it drops to the radiators - It is the one main flow pipe for heating and hot water

 

[ShaunCorbs]

Can you take a picture of one of your rads please?

 

[chloeradhsaw]

Here is an example. Many radiators are like that with hot at top and flow at bottom

I am certain it is a one pipe system because I had a viessman engineer come to install a system who told me it is a one pipe

Most pipework is 3 inch or 2 inch steel pipework and there are slight drops in the loft to keep the water moving

 

[chloeradhsaw]

i was told on the diynot forum that the flow pipe to the hot water cylinder is not horizontal but inclines upwards and could catch air and be airlocked

I found that difficult to understand because the air vent is much higher then even the highest part of the flow pipe but I am not experienced in this

What options do I have ? So far I think

1) rebend the pipework so it is downwards inclined
2) add a pump after the two port valve
3) use 28mm instead of 22mm for the flow pipe to hit water cylinder

I anyway want to replace the boiler with a heat only inter gas 30kw but before I do that I need to make sure the system works properly otherwise it’s thousands wasted

 

[ShaunCorbs]

200% won’t be the reason the cylinder isn’t suitable for gravity due to the coil so you will have to swap the cylinder or convert to a fully pumped system eg install another 2 port on the rad circuit

New boilers don’t really like 1 pipe systems so I would be advising repipe