What's this heating system???

[tackit]

I recently moved and think I might need a new boiler soon and I'd like to know what boiler would be a good like for like.

It has an Ideal Mexico Super 70FF (circa 1999) sounds rough at times, but works!

The system has three tanks in loft, one small f&e and two larger water storage tanks that supply bath and shower cold water and to the hot water cylinder.

It has a hot water cylinder with top and bottom immersion heaters, and has a pump next to it to circulate the hot water from boiler through tank.

And another pump next to boiler for the central heating (looks new).

It has a British Gas UP1 controls unit and no room thermostat.

The current boiler has 4 pipes out of the cast iron heat exchanger, most new boilers I've quickly looked at just have two (flow and return).

What is this system and what boiler would be best fit to replace, can be wall mounted or floor as enough space.

I really like the system as it is, but would probably like some more modern controls plus room thermostat.

 

[Hugh Jaleak]

Some photos would be handy, but from the description you may have Pumped Central Heating/Gravity Hot Water Primaries, pump adjacent to cylinder may be a Secondary Circulation for the Hot water supply. Are the pipes from the Boiler a pair of 22mm (3/4" with the pump fitted to one) and a pair of bigger 28mm (1") going upwards towards the cylinder location?

Fully Pumped would be the way to go, but assuming you have Gravity HW, some control could be put on the existing system should you want to, converting to a 'C Plan' would probably be the easiest option in the short term.

 

[Ollyfp]

Don't rush into this. You might find that there's a very simple heating system that fits perfectly with your lifestyle, but you might choose to sacrifice certain creature comforts for the sake of economy.
I'm one of the seven people in the UK who are happy running an ASHP system!

 

[tackit]

Thanks Hugh.

All pipes go down under floor.

Yes two 22mm pipes and two 28mm pipes diagonally on heat exchanger. But all 22mm pipe used and in pairs vertically.

So I assume a pump is being used to move the hot water from the boiler through the coil in the cylinder to get the water around, rather than using 28mm pipe going up from boiler and hot water rising system like in our last house.

So what's this system called?

Most new boilers I see just have one flow and return, not two like now. How would a new boiler fit here to keep things the same?

As mentioned, I really like the whole system. I also like that I can heat water on economy 7 or gas.

 

[avonmouth]

It's fully pumped.The pump by the boiler is for heating and the other pump is for hot water.
There will be thermostats controlling the pumps.

 

[fixitflav]

So I assume a pump is being used to move the hot water from the boiler through the coil in the cylinder to get the water around, rather than using 28mm pipe going up from boiler and hot water rising system like in our last house.

Correct

So what's this system called?

I don't think it has a name, it's somewhat unusual

Most new boilers I see just have one flow and return, not two like now. How would a new boiler fit here to keep things the same?

You could put a tee on the flow pipe, to feed both pumps.

Unless you have a big house, unlikely it needs 70000 BTU/h (20.5 kW)

With your system, I'd expect when 1 pump is running, there is reverse flow through the other pump and circuit. Have you noticed this, and is it a problem? I'd expect worse in summer when the HW pump is running and the rads get warm, last thing you need in a heatwave!

I don't see why you couldn't install a roomstat, but depending on the house layout, it might be not be too easy running a wire from the best roomstat location back to the boiler or programmer.

With 2 pumps, it must be wired using double-pole switches, or relays oe something, so that when 1 pump runs (and the boiler fires) the other pump doesn't run.
In case you haven't got the boiler manual, it's attached.

Mexico FF

 

[tackit]

Thanks again, fixitfav.

So if I get a new regular gas boiler fitted I want either an S plan or Y plan system with zone valves using just one flow and return to the boiler.

Allen Hart YouTbue been very useful too on this subject.

 

[ericmark]

I can heat water on economy 7 or gas.

Economy 7 can work out expensive, as you pay more for electric when not off-peak. I have a split tariff, and it saves me a lot of money, but to get that saving I also have a battery to store the off-peak.

Thanks again, fixitfav.

So if I get a new regular gas boiler fitted I want either an S plan or Y plan system with zone valves using just one flow and return to the boiler.

Allen Hart YouTbue been very useful too on this subject.

I see no point in on/off zone valves, unless, like me, you have a section of the house unused most of the time in winter. I have a zone valve to turn off the flat under the main house, but in the main house the TRV's control what room is heated, to what temperature and when.

Using programmable TRV heads, I can set a sequence, only a few minutes between each room, but it means rooms can reheat faster, I have 10 programmable TRV heads, so only heat when required. I have a rather old boiler in this house, likely 30 years old, but it works fine, it depends on how well the boiler was made to start with.

Modern gas boilers gain the latent heat from the flue gases, to do this the return water needs to be below a set temperature, so the boiler is designed to modulate (turn down the output) if the boiler is switched off by an external device, then it has to start again working out the output required, so the idea is where one can, to use analogue control, and the TRV does just this, slowly opening or closing a little, using an on/off zone valve is a bad idea with a modern boiler.

However, unless using an expensive thermostat with the likes of OpenTherm, the boiler has no way to know when it is no longer required, so the method often used is to have a hub, which can have either wall thermostats, or direct to the TRV heads, to tell the boiler when no longer required. I have three devices which will fire the boiler.

 

[fixitflav]

So if I get a new regular gas boiler fitted I want either an S plan or Y plan system with zone valves using just one flow and return to the boiler.

You were asking about how to keep the two pump system. For a one pump system I would go for W-plan.