Fully pumped CH & HW, no motorised valves!

[Rhys_91]

Hi

I bought a house about 3 years ago which was build in the mid 80's. It's in a large housing estate and my neighbours have the same type of heating system - it doesn't seem to match any heating 'plan' I can find in the internet and it's driving me crazy!!

I'll try to explain it the best I can.

It'a a open vented system (F&E tank fill pipe is blocked, but that's an issue for another day! You'll see from the photo I refilled the system using the HW vent pipe and a hose pipe the last time I drained the system down), gas boiler and microbore piping to all radiators. System is fully pumped. Boiler in utility room (moved there as part of small extension about 20 years ago) and pump still in the kitchen behind the cupboards. There are no heating controls as such, just an old Sangamo timer switch.

There is NO separate control for heating and hot water, it's either both on or both off. So for hot water in the summer, all rads have to be turned off at the TRV's. There are no motorised valve to switch between hot water and heating, effectively the hot water coil is simply a giant radiator.

As annoying as this is, I'm not interested in getting the system modified to add separate heating and hot water control as I don't want the expense.

One of the problems I've had is the radiators never seems to get hot to the touch, they only get warm at best (although I always have a constant supply of scolding hot water!!). Now, the hot water cylinder is fed by 22mm piping and the radiators by microbore, so my guess is that water will always take the path of least resistance and is constantly circling around the hot water tank and minimal heat gets down the microbore to the radiators.

My question is, if I get a plumber to fit a shut off/gate valve in the airing cupboard just before the hot water tank, this would reduce the flow going through the tank and increase the flow going around the radiators. A bit like a manual motorised valve if that makes sense?? I don't think I can go another winter having to leave the heating on 24/7 just for a bit of heat - it takes several hours to heat up a 3 bedroom house at the moment!

Does anyone see any flaw in my plan?

Thanks for any help.

Cheers

Rhys

 

[flameport]

As annoying as this is, I'm not interested in getting the system modified to add separate heating and hot water control as I don't want the expense.

With no controls, you are throwing money away every time the system is switched on.

Two 2 port valves, a cylinder thermostat and a basic room thermostat will make a vast difference to how the system operates and reduce the running cost significantly.

 

[garyo]

Does anyone see any flaw in my plan?

That would give you the equivalent of a balance valve on the tank and therefore ability to establish if there's another problem with the rads such as blocked microbore, but you know ultimately you'll still need to fit some form of independent control like a separate pump or motor valve.

 

[dal5band]

Just one point - where in the circuit is the HW primary takenfrom. If it is part way round then it would be difficult to separate off the CH. You can cetainly control the HW temp with a valve next to the HW cylinder, controlled by a thermostat strapped to the cylinder. I think you should take the power for the valve from the same point as the boiler.

 

[Rhys_91]

Thank you all for your responses.

Flameport, I know, truly I know I need to get the work done as the current set up is beyond inefficient. It just seems too much of an initial expense at the moment - The boiler is in the utility room, pump in the kitchen but the pump is not wired to the boiler, it's wired directly to the Sangamo timer so when the boiler's thermostat shuts the boiler off, the pump still runs continuously until the timer shuts down the whole system. There is one manifold for the downstairs radiators under the floor in the under stairs cupboard, but this only has 6 pipes coming from it (x2 for return) so there must be another manifold upstairs for the upstairs rads - I don't know the location. So I have no idea where the hot water and heating pipes actually meet to get a valve fitted. The whole system needs rewired and sections repiped by the looks of it and I'm guessing there will be several sections of plaster damaged to get this done - the potential cost makes me shudder at the moment.

Garyo - I'm pretty certain there are no blockages - a few weeks ago I drained the whole system down to clean out all the sludge. Each radiator refilled with no bother.

Dal5band. I don't think a cylinder stat & valve alone would work at the moment - the boiler and pump are only controlled by an electronic timer, so if the stat closed the valve, there is no way for the pump to then shut down. I'd need everything rewired to achieve this.

I'm hoping the manual isolation value fitted to the hot water tank will increase the temperatures to the radiators as a temporary measure until I can get the whole central heating system upgraded.

My house was build by Bredero Homes, which built several estates over Aberdeen/Aberdeenshire - I am struggling to believe that every house built by them has had a central heating system so badly designed that each home has never had hot radiators.....

 

[DP]

Here goes.
System installed by FEP
Your cylinder has been replaced
Normally the bottom connection was run in 8mm microbore, top 15 to carry on to header cistern to then split as vent and feed.
Boiler often was a Baxi WM some such.

Radiators not heating because excess circulation through 22mm pipe to cylinder

BTW, boiler does not control the pump, timer does

Also, you have a blockage in the top pipe around that tee is My guess

WHERE YOU HAVE FITTED THE VALVE AND HOSE CONNECTION, RESTORE THAT PIPE AND REMOVE THE VALVE. You have now got a sealed installation with no expansion. YOU COULD HAVE A BLOWOUT AND INJURY COULD TAKE PLACE IF NOT A FATALITY

 

[dal5band]

Hope there is a separate F&E pipe somewhere else ! That pipe next to the cylinder looks like just an air vent ?
However DP you have hit on the problem of the cold rads - the bottom pipe from the cylinder should be restricted so you can balance the flow - a manual rad valve would do.

 

[Rhys_91]

Here goes.
System installed by FEP
Your cylinder has been replaced
Normally the bottom connection was run in 8mm microbore, top 15 to carry on to header cistern to then split as vent and feed.
Boiler often was a Baxi WM some such.

Radiators not heating because excess circulation through 22mm pipe to cylinder

BTW, boiler does not control the pump, timer does

Also, you have a blockage in the top pipe around that tee is My guess

WHERE YOU HAVE FITTED THE VALVE AND HOSE CONNECTION, RESTORE THAT PIPE AND REMOVE THE VALVE. You have now got a sealed installation with no expansion. YOU COULD HAVE A BLOWOUT AND INJURY COULD TAKE PLACE IF NOT A FATALITY

Brilliant, that would explain it. I have a plumber coming in the next few days to fit an isolation valve. If, for example, I only half close the valve or so where in between, this should hopefully restore balance and give me hot radiators and hot water.

Just to clarify, the pipe where I added the hose pipe is an air vent. I only added the hose connection temporarily so I could refill the system as the feeder tank is blocked.
You cant see it in the photo, but the tank has a pipe coming out the top which goes into a tee by the wall - down for the hot water to the taps and up as the expansion vent.

Cheers

 

[Rhys_91]

Thanks again for the responses.

Final question and I feel a bit silly asking, but does it matter if the valve goes on the feed or return of the hot water tank? In my head I can’t see it making difference. It looks easier to put it on the return as theres more pipe to play with

 

[DP]

Just to clarify, the pipe where I added the hose pipe is an air vent. I only added the hose connection temporarily so I could refill the system as the feeder tankNsion is blocked.
You cant see it in the photo, but the tank has a pipe coming out the top which goes into a tee by the wall - down for the hot water to the taps and up as the expansion vent.

You cannot have just a vent there. The pipe must terminate at the feed and expansion cistern. When boiler switches on and fires the burners, heats primary water, expansion goes into the cistern as is, it does not.

 

[Rhys_91]

Hopefully this picture clarifies the set up

 

[dal5band]

DP is right - that expansion pipe coming out of the HW tank is the HW side expansion - nothing to do with the boiler. The boiler must have a separate expansion to the small f&e tank which you say is blocked - get the plumber to cut out the blocked bit and replace it.

 

[dilalio]

Hopefully this picture clarifies the set up

Oh dear.

 

[DP]

I would say lucky so far if there are no
Leaks or system popping. A Baxi WM would have blown a seal if heating was fired up

 

[Rhys_91]

Forgive my ignorance but I don’t follow the concerns...

Where I filled using a hose pipe is simply an air vent pipe for the hot water heating coil. The pipe out the top of the tank which goes to the tee junction goes down to feed the taps with hot water and up is the expansion pipe for hot water which goes to the big tank in the loft.

The expansion pipe for the heating & hot water coil is at the other end of the house (near the pump) and has its own pipe going into the loft into the smaller tank. The expansion pipe for the heating isn’t blocked ( I know this as I over filled the system and it started coming out the expansion pipe) it’s the feed pipe that’s blocked. Unfortunately where the feed pipe meets the system is under the kitchen floor which is tiled, so a big job to get done.