Help with underfloor heating

Robinhood

My mums underfloor heating does not appear to be operating correctly and is getting way too hot. It’s as if the thermostatic valves aren’t operating as they should. Regardless of position of thermostat the temperature on the flow manifold always gets to in excess of 60 degrees. Any ideas why this could be?

I think I’m going to have to get the system overhauled and have been quoted £1690 plus vat. Does this seem a reasonable quote for replacing two 7 way manifolds. I’m led to believe the existing manifolds are no longer available so the quote also covers replacing the actuators and two new pumps.



Thanks in advance for any advice.

Update - The quote is £1130 for materials & £560 for labour

J_B

In your top photo, the flow (?) temperature looks to be 70+C which is way too hot.

Surely the TRV below the pump should be controlling this (?) - have you tried altering it?

I'm slightly confused as the top photo has a Bosch pump and 7 manifolds whereas the other two have a Grundfos pump and five manifolds!

Rodders53

Looks like two sets of UFH manifolds, circulating pumps and Thermostatic mixer valves (with remote phials).
Upstairs and Down?

Immediately turn the boiler stat down to a much lower temperature... 50C or lower even...  (Big issue will eventually be one of lack of really hot water in the tank, but 50C will probably be ok for short term while a proper fix is researched).

The thermostatic actuator valves / remote phials will be the most likely culprits.  Turn them to a lower number = cooler for a start to see if they are working?

Test each room thermostat opens/closes the appropriate actuator.  My UFH manifold has flow meters where the red caps/balancing brass bits are are to see which loops have flow or not.  More difficult to know otherwise, perhaps?

If they all work then why replace the lot?

Seek out the manuals and read them?

I replaced my equivalent thermostatic actuator mixer valve with a simple manual mixer valve but the phial was bodged to the return manifold with tape and ty-raps.

Robinhood

J_B said:

In your top photo, the flow (?) temperature looks to be 70+C which is way too hot.

Surely the TRV below the pump should be controlling this (?) - have you tried altering it?

I'm slightly confused as the top photo has a Bosch pump and 7 manifolds whereas the other two have a Grundfos pump and five manifolds!

Agreed. Tried TRV on lowest setting and still in excess of 60 degrees.
Upstairs and downstairs. Bosch pump is downstairs.

Robinhood

Rodders53 said:

Looks like two sets of UFH manifolds, circulating pumps and Thermostatic mixer valves (with remote phials).
Upstairs and Down?

Immediately turn the boiler stat down to a much lower temperature... 50C or lower even...  (Big issue will eventually be one of lack of really hot water in the tank, but 50C will probably be ok for short term while a proper fix is researched).

The thermostatic actuator valves / remote phials will be the most likely culprits.  Turn them to a lower number = cooler for a start to see if they are working?

Test each room thermostat opens/closes the appropriate actuator.  My UFH manifold has flow meters where the red caps/balancing brass bits are are to see which loops have flow or not.  More difficult to know otherwise, perhaps?

If they all work then why replace the lot?

Seek out the manuals and read them?

I replaced my equivalent thermostatic actuator mixer valve with a simple manual mixer valve but the phial was bodged to the return manifold with tape and ty-raps.

Yes, upstairs and down. Boiler control only has a max and min, no markings in between. Currently set to below halfway. I turned it down a bit earlier but will turn it down further now.

The thermostatic actuator valves / remote phials are my suspicion too. They are currently set to lowest setting and temperature is still well in excess of 60 degrees.

All room stats and actuators are in working order.

Reason for replacing the lot is I suspect the excessive heat has done damage to seals etc. Both manifolds have multiple leaks. I’d be more inclined to try and repair the leaks if it was my heating system, but with it being my mums who is almost 80 I just want a reliable system.

fenwick458

My UFH TRV only goes to 50, and I have it set at 40 thats plenty.. if you have a TRV designed for a radiator and it's set at the bottom of the range it probably wasn't designed to be functioning at that temp so might be way off.
honestly the quote seems expensive and to me it seems like the person who has quoted doesn't have the knowledge to find the faulty part and just wants to replace the whole lot to make their life easier.
seals can be replaced, leaks can be fixed, single faulty parts can be fixed..
how long has it been like this?
the zone actuators aren't thermostatic either and are unlikely to be faulty, well I've never found a faulty one yet. they are incredibly simple it's just a block of wax that gets melted

Robinhood

fenwick458 said:

My UFH TRV only goes to 50, and I have it set at 40 thats plenty.. if you have a TRV designed for a radiator and it's set at the bottom of the range it probably wasn't designed to be functioning at that temp so might be way off.
honestly the quote seems expensive and to me it seems like the person who has quoted doesn't have the knowledge to find the faulty part and just wants to replace the whole lot to make their life easier.
seals can be replaced, leaks can be fixed, single faulty parts can be fixed..
how long has it been like this?
the zone actuators aren't thermostatic either and are unlikely to be faulty, well I've never found a faulty one yet. they are incredibly simple it's just a block of wax that gets melted

It’s been like this for far too long, probably in excess of 6 months. The UFH used to work fine (actually really well) so I’d say the TRV’s are the correct ones. Although they are marked like radiator TRV’s e.g, 1-5, not degrees. They just don’t appear to be working properly now.

Quote seems a little excessive to me too, possibly by £300ish. I guess it’s a bit of a trade off between materials and labour. In some ways I’d be happy to replace it for peace of mind. So I’m going to try and get another couple of quotes.

J_B

Couldn't they just try replacing the TRV's to start with?

Robinhood

J_B said:

Couldn't they just try replacing the TRV's to start with?

Yes but manifolds are also leaking from just about every port on the return manifold requiring boiler to be topped up daily, so not a small leak. Downstairs also leaks from the pump too.

From what research I’ve done the existing manifolds are obsolete so is it better just to bite the bullet now?

J_B

Happy New Year!

What we just did was ..... new everything downstairs and kept the old bits (which are the same in our case) as spares for upstairs (*)

* = we rarely use the upstairs heating!

fezster

Robinhood said:

J_B said:

Couldn't they just try replacing the TRV's to start with?

Yes but manifolds are also leaking from just about every port on the return manifold requiring boiler to be topped up daily, so not a small leak. Downstairs also leaks from the pump too.

From what research I’ve done the existing manifolds are obsolete so is it better just to bite the bullet now?

I'd call another plumber in. It seems absurd to replace a perfectly good system. Most leaks can be fixed even if original parts are not available and the TRV is clearly faulty, so should be a straightforward fix to the excess temperature.